Paramount Fitness ME II User manual

Copyright 2015 Software Bisque, Inc. All rights reserved.
The Paramount Robotic Telescope System
User Guide
Paramount ME II, MYT, MX, and MX+ models
Revision 1.94 August, 2015

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Information in this document is subject to change without notice and does not represent a commitment
on the part of Software Bisque. The software products described in this document are furnished under a
license agreement or nondisclosure agreement. They may be used or copied only in accordance with the
terms of the agreement. It is against the law to copy the software on any medium except as specifically
allowed in the license or nondisclosure agreement. The purchaser may make one copy of the software
for backup purposes.
No part of this manual and/or databases may be reproduced or transmitted in any form or by any means,
electronic or mechanical, including (but not limited to) photocopying, recording, or information storage
and retrieval systems, for any purpose other than the purchaser's personal use, without the express
written permission of Software Bisque, Inc.
Software Bisque
862 Brickyard Circle
Golden, CO 80403-8058
USA
Web Site: http://www.bisque.com
The Paramount ME, Paramount ME II, Paramount MX, Paramount MX+, Paramount MYT, Bisque TCS, MKS
4000, MKS 5000, and TheSkyX Professional Edition Astronomy Software are trademarks of Software
Bisque, Inc.
All other product names are trademarks of their respective owners and are used solely for identification.

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Table of Contents
Telescope Operation Disclaimer ................................................................................................................... 8
Sun Warning.................................................................................................................................................. 8
The Paramount Robotic Telescope System .................................................................................................. 9
Paramount Model Comparison............................................................................................................... 12
Optional Accessories............................................................................................................................... 14
Getting Help................................................................................................................................................ 15
What You Need to Know............................................................................................................................. 15
Coordinate Systems ................................................................................................................................ 16
The Horizon Coordinate System .........................................................................................................16
The Equatorial Coordinate System .....................................................................................................17
Hour Angle ..........................................................................................................................................18
Local Sidereal Time ................................................................................................................................. 19
Atmospheric Refraction .......................................................................................................................... 19
Polar Alignment Basics............................................................................................................................20
Homing....................................................................................................................................................22
Labeling the Home Position on the Sky Chart.....................................................................................23
Physically Marking the Home Position................................................................................................ 24
Synchronization ......................................................................................................................................25
Best Synchronization Practices ...........................................................................................................26
Step by Step Synchronization .............................................................................................................26
Session to Session Pointing Repeatability........................................................................................... 27
Making Sure Synchronization Is Correct ............................................................................................. 28
The Local Celestial Meridian ...............................................................................................................29
Maintaining Accurate Time.................................................................................................................30
Parking the Paramount ........................................................................................................................... 31
Parking from TheSkyX Professional Edition ........................................................................................ 31
Defining the Park Position...................................................................................................................32
Park Position Rules.............................................................................................................................. 32
Audible Control System Feedback ......................................................................................................32
Visual Control System Feedback ......................................................................................................... 35

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Through the Mount Cabling................................................................................................................35
Packing List.................................................................................................................................................. 41
Box 1 Contents........................................................................................................................................ 41
Important Packing Material Notes...................................................................................................... 43
Box 2 Contents (Accessories Box) ........................................................................................................... 44
Locating Your Serial Numbers.............................................................................................................47
Paramount and Software Serial Number Registration ...........................................................................48
Unpacking the Paramount .......................................................................................................................... 48
Your Safety is Paramount........................................................................................................................ 48
Paramount ME II Unpacking Insert ..................................................................................................... 49
Paramount MX Unpacking Insert........................................................................................................50
Paramount MX+ Unpacking Insert......................................................................................................51
Paramount MYT Unpacking Insert ...................................................................................................... 52
Packing the Paramount for Transport ....................................................................................................54
Paramount Components............................................................................................................................. 55
Paramount ME II Front View...................................................................................................................56
Paramount MX Front View .....................................................................................................................57
Paramount MX+ Front View ...................................................................................................................58
Paramount MYT Front View....................................................................................................................59
RA Worm Block Cover......................................................................................................................... 59
Payload Mounting Plate (Versa-Plate)................................................................................................60
Paramount Versa-Plate Knobs ............................................................................................................ 63
Large Dovetail Accessory Rail (Paramount ME II only, Optional) .......................................................68
Instrument Panel.................................................................................................................................68
RA Worm Block Cover......................................................................................................................... 72
RA Cable Conduit ................................................................................................................................ 72
RA Gear Cover (ME II Only) .................................................................................................................72
Dec Cable Conduit...............................................................................................................................72
Right Ascension Carrying Handle ........................................................................................................72
RA Worm Block Switch........................................................................................................................ 73
RA Spring Plunger and Cam Stop Access Hole (Paramount ME II and MX+ Only)..............................77
RA Encoder Cover (Paramount ME II Only)......................................................................................... 77

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RA Assembly........................................................................................................................................ 77
Electronics Box....................................................................................................................................77
Polar Axis Adjustments .......................................................................................................................81
Azimuth Adjuster Knobs .........................................................................................................................82
Base Thrust Mounting Knobs..............................................................................................................84
Base Plate............................................................................................................................................84
Paramount ME II Rear View....................................................................................................................85
Paramount MX Rear View....................................................................................................................... 86
Paramount MX+ Rear View.....................................................................................................................87
Declination Carrying Handle (Paramount MX Only) ...........................................................................88
Declination Axis Three Position Switch (Paramount MX Dec Three Position Switch) ........................88
Cable Conduit Access Hole and Cover ................................................................................................ 88
Right Ascension Axis Locking Hole (Paramount ME II Only) ...............................................................89
Configurable Hard Stop Positions (Paramount ME II Only) ................................................................90
Declination Axis Assembly (Dec Assembly)......................................................................................... 90
Paramount Serial Number (Serial Number)........................................................................................91
Altitude Scale ......................................................................................................................................91
Altitude Adjuster.................................................................................................................................93
Counterweight Shaft...........................................................................................................................98
Counterweight Shaft Extension Bar (Optional)................................................................................... 99
Counterweights................................................................................................................................... 99
Payload Imbalance Cause and Effect ................................................................................................ 101
Balancing the Payload....................................................................................................................... 101
Counterweight Safety Knob ..............................................................................................................102
Paramount ME II Side View................................................................................................................... 103
Paramount MX Side View ..................................................................................................................... 104
Paramount MX+ Side View ...................................................................................................................105
Altitude Adjuster Thrust Knobs.........................................................................................................106
Wedge............................................................................................................................................... 106
Bubble Level...................................................................................................................................... 107
Declination Axis Locking Hole (Paramount ME II Only) .................................................................... 108
Micro Levelers (Paramount ME II Only)............................................................................................108

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Hand Controller................................................................................................................................. 110
Other Paramount Accessories ..............................................................................................................111
USB 2.0 Cable ....................................................................................................................................111
Hex Wrenches ...................................................................................................................................112
Power Supply Unit (PSU)...................................................................................................................112
Altitude Adjuster Wrench (Paramount ME II Only) ..........................................................................112
How To Polar Align....................................................................................................................................112
Rough Polar Alignment Method ...........................................................................................................113
Step-By-Step Rough Polar Alignment ............................................................................................... 113
Accurate Polar Alignment .....................................................................................................................114
Using TheSkyX Pro for Precise Polar Alignment................................................................................ 114
Using the Polar Alignment Scope...................................................................................................... 115
The Paramount and TheSkyX Professional Edition ...................................................................................116
Paramount Minimum System Requirements .......................................................................................116
First Time Paramount Setup .................................................................................................................117
Paramount USB Driver Installation .......................................................................................................117
Mac OS X ...........................................................................................................................................118
Windows ...........................................................................................................................................118
Controlling the Paramount with TheSkyX Professional Edition............................................................118
Getting Started with TheSkyX Professional Edition .............................................................................. 119
The Bisque TCS Window ....................................................................................................................... 120
Status Messages (Status Text) ..........................................................................................................121
Firmware Version and Mount Identifier ........................................................................................... 121
Parameters Tab..................................................................................................................................... 121
Advanced Parameters....................................................................................................................... 124
Commands Pop-up Menu ................................................................................................................. 131
Show Status Tab.................................................................................................................................... 135
Periodic Error Correction Tab ...............................................................................................................137
Bisque TCS PEC Table Tab .................................................................................................................138
Compute PEC Curve Tab ................................................................................................................... 140
Collecting and Using Periodic Error Tracking Data ...............................................................................142
Utilities Tab .......................................................................................................................................148

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Logging Tab ....................................................................................................................................... 164
Using ProTrack™ ....................................................................................................................................... 164
ProTrack Minimum Requirements....................................................................................................164
Getting Started with ProTrack ..........................................................................................................165
Troubleshooting Mount Operation...........................................................................................................166
USB Hubs and USB Extenders ...............................................................................................................167
Controlling Multiple USB Devices with USB Hubs............................................................................. 167
Windows and USB Port Power Settings............................................................................................168
Appendix A: Installing the MKS 5000 USB Windows Driver ..................................................................... 170
Windows USB Driver Installation and Use ............................................................................................ 170
Accessing Windows Device Manager................................................................................................ 171
Uninstalling the MKS 5000 Driver ..................................................................................................... 172
Appendix B: Paramount Technical Drawings............................................................................................174
Computing Dome Offset Distance ........................................................................................................175
Appendix C: External Power Cable Sets .................................................................................................... 178
Apogee/QSI/SBIG ST-402/STF-8300 Model Camera External Power Cable Set Specifications ............ 178
SBIG ST-7 Series (5-Pin) External Power Cable Set Specifications ........................................................ 181
SBIG ST-L Series (6-Pin) External Power Cable Specs............................................................................182
Finger Lakes Instruments External Cable Specs....................................................................................184
Generic External Power Cable Specs ....................................................................................................185
Appendix D: Paramount Warranty ........................................................................................................... 187
MKS 5000 Warranty Replacement Procedure and Policy..................................................................... 187
MKS 5000 Non-Warranty Replacement Procedure and Policy............................................................. 188
Shipping Address...................................................................................................................................188
Appendix E: Revision History ....................................................................................................................189
Index..........................................................................................................................................................192

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Telescope Operation Disclaimer
Robotic telescope mounts do not have an unlimited range of movement. The telescope’s shape, the way
it is mounted, or the addition of accessories can prevent it from pointing at particular parts of the sky. If
the telescope is forced past these points, the telescope, its mounting, or accessories might be damaged.
TheSkyX Professional Edition includes telescope limit features that let you define these inaccessible
positions; TheSkyX Professional Edition, or the mount’s control system, will try to prevent the telescope
from entering or crossing them. This feature is provided as a convenience, not as a panacea. Since any
telescope can run into its mechanical limits through accident, carelessness, or component failure,
Software Bisque cannot be responsible for any damage to your telescope that occurs when using TheSkyX
Professional Edition to control it.
Furthermore, Software Bisque cannot be held responsible for damage caused by plugging cables into
electronic devices. We strongly recommend turning off all electronic devices (computers, mobile devices,
telescopes, focusers, dew heaters, CCD cameras, etc.) before attaching any cabling or power supplies.
Sun Warning
NEVER attempt to observe the Sun through your telescope! Without
a specially designed solar filter, viewing the Sun –for even a fraction of
a second –will cause instant, irreversible eye damage. When observing
during the day, do not point the telescope near the Sun. Do not use
TheSkyX Professional Edition’s automatic slew feature to find objects
during the day.

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The Paramount Robotic Telescope System
Thank you for purchasing the Paramount Robotic Telescope System. The Paramount mount is an ultra-
precision German equatorial mount (GEM) that is designed to deliver unmatched pointing, tracking and
stability for amateur or professional astronomers in portable or permanent installations. These precision
mechanics, when commanded TheSkyX Professional Edition, create a formidable imaging system that can
help you achieve your most lofty observing goals.
This user guide covers the basic setup and use of the Paramount ME II, Paramount MX, Paramount MX+,
and Paramount MYTmodel mounts, as well as how to control your mount using TheSkyX Professional
Edition.
This document assumes you are familiar with many fundamental concepts in astronomy and are
somewhat experienced using a telescope and or CCD camera in conjunction with a personal computer.
If a concept presented here is new to you, consider searching the Internet to find out more information
about it. Unfortunately, there is simply no way that all the different facets of setting up and controlling a
robotic telescope mount can be covered in a single document.
The table below lists the significant Paramount hardware, electronics and software features that are
designed to help foster memorable and productive observing experiences.
Feature
Software Bisque’s fourth
generation dual axis control system
(MKS 5000™) provides precision,
reliable performance.
Integration with TheSkyX
Professional Edition for Mac or
Windows control.
Camera Add On™ software provides
single software telescope, camera,
focuser, filter wheel, SBIG AO and
rotator control.
Dome Add On™ keeps the
motorized dome aligned with
telescope.
-
-
-
TPoint Add On™ with Super
Model™ and ProTrack™ provides
the same telescope pointing
correction software that is used on
most professional telescopes.

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The Multi-OS and Six License Add
On lets you install TheSkyX
Professional Edition and related
Add Ons on up to six (6) different
Mac and Windows computers.
Research-grade right ascension
gears with seven (7) arcsecond or
less peak to peak periodic error
before training PEC.
Optimal periodic error correction
curve fitting that can produce
“seeing indifferent” periodic error
curves.
Direct Guide™ allows optimal
guiding without a guider cable.
Both the right ascension and
declination axes include mechanical
switches to change quickly switch
between balancing the payload and
tracking.
The Paramount ME II’s axes
may be locked in place by
installing locking bolts
(page 89).
The Paramount MX
includes a three position
mechanical switch (page
50).
Each axis of the Paramount
MX+ and Paramount MYT
has two separate
mechanical switches (page
52).
Clutch-free worm block design
preserves the mount’s physical
orientation for accurate and
repeatable TPoint modeled
pointing and tracking.

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The control system supports a wide
dynamic range for slewing and
tracking rates. Virtually any slew
speed is available between zero
and several degrees per second.
Configurable acceleration and
deceleration rates during slews.
Integrated homing sensors that
allow rapid mount initialization to
produce precision and reliable
repeatability from night to night, or
if power is lost.
Super-stable physical design that
rapidly dampens external
vibrations.
Configurable software slewing
limits prevent damage to the
mount and telescope by slowly
decelerating to limit regions.
Clutch-free design ensures
consistent pointing and tracking
from night to night.
Fifty individual through the mount
cabling conductors that help
minimize the tedium of having CCD
power, CCD signal, focus, video,
dew heater, and other accessory
cables routed to the telescope.
Integrated Cable Conduit™ allows
adding custom cables, wires
through the mount.
Integrated rotating base allows
calibrated azimuth adjustments to
be made without affecting the
mount’s altitude.
Integrated altitude scale to provide
an accurate altitude starting point
for polar alignment.

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Paramount Model Comparison
The Paramount ME II, Paramount MX and Paramount MX+ are very similar in function and design. The
table below lists the “significant”differences between these models.
Feature or
Specification
Maximum payload
capacity (total
instrument
capacity not
including
counterweights)
109 kg/240 lb.
41 kg/90 lb.
45 kg/100 lb.
23 kg/50 lb.
Physical
dimensions
See technical
drawing
references on
page 174.
See technical
drawing
references on
page 174.
See technical
drawing
references on
page 174.
See technical
drawing
references on
page 174.
Structural design is extremely rigid,
even at maximum payload capacity.
Landing lights under the mount can
be turned on to illuminate dark
working areas during setup.
Two counterweights and one
counterweight shaft included
standard.
Oversized right ascension and
declination bearings provide
maximum stability.
20.3 cm
(8 in.)
15.2 cm
(6 in.)
15.2 cm
(6 in.)
11 cm
(4.3 in.)
Integrated equatorial wedge for
polar axis altitude adjustment.
14° –68°
10° –65°
10° –65°
0° –64°
High total instrument capacity to
mount weight ratio.
109 kg/38 kg
(240 lb./84
lb.)
41 kg/23 kg
(90 lb./50 lb.)
45 kg/23 kg
(100 lb./50
lb.)
23 kg/15.4 kg
(50 lb./34 lb.)
Power supply included with mount.
200W max
80W max
80W max
80W max

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Feature or
Specification
Versa-Plate
dimensions and
optional mounting
accessories (page
60)
25 cm x 51 cm x
2.5 cm
(9.9-in. x 20-in. x
1.0-in)
Four dovetail
mounting
knobs.
Optional
mounting
rails for
attaching
large OTAs.
16 cm x 41 cm x
1.8 cm
(6.4-in. x 16-in x
0.72 in.)
Three
dovetail
mounting
knobs.
16 cm x 41 cm x
1.8 cm
(6.4-in. x 16-in x
0.72 in.)
Three
dovetail
mounting
knobs.
15 cm x 35.6 cm x
1.6 cm
(5.95-in. x 14-in x
0.63 in.)
Three
dovetail
mounting
knobs.
Number of Altitude
Adjuster Thrust
Knobs (page 106)
Four (4)
Two (2)
Two (2)
Two (2)
Routing custom
cabling through
the mount
See “Through the
Mount Cabling”
on page 35 for
details.
See “Through the
Mount Cabling”
on page 35 for
details.
See “Through the
Mount Cabling”
on page 35 for
details.
See “Through the
Mount Cabling”
on page 35 for
details.
Mechanical switch
on right ascension
and declination
axes (page 73)
The Two Position
Switch engages
the worm with
the gear, or
permits payload
balance by
separating the
worm from the
gear.
The right
ascension and
declination axes
can be locked in
place for
transport, or
when adding
payload, by
installing two
locking bolts on
each axis.
The Three
Position Switch
engages the
worm with the
gear, permits
payload balance
by separating the
worm from the
gear, or locks the
gears to prevent
axis rotation
during shipment
or transport.
The Two Position
Switch engages
the worm with
the gear, or
permits payload
balance by
separating the
worm from the
gear.
The
Transportation
Lock Knob can be
placed in a lock or
balance position
for transportation
or adding payload
by pulling and
rotating a
mechanical
switch 90 degrees
for each axis.
The Two Position
Switch engages
the worm with
the gear, or
permits payload
balance by
separating the
worm from the
gear.
The
Transportation
Lock Knob can be
placed in a lock or
balance position
for transportation
or adding payload
by pulling and
rotating a
mechanical
switch 90 degrees
for each axis.

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Feature or
Specification
Physical hard stops
that permit
tracking past the
meridian without
the optical tube
assembly flipping
sides
Configurable.
Five different
positions, located
at a minimum of
seven minutes to
up to two (2)
hours past the
meridian.
Fixed, non-
configurable hard
stop position that
allows a
maximum of two
(2) hours tracking
past the
meridian.
Fixed, non-
configurable hard
stop position that
allows a
maximum of two
(2) hours tracking
past the
meridian.
Fixed, non-
configurable hard
stop position that
allows a
maximum of two
(2) hours tracking
past the
meridian.
Base Plate Micro
Levelers
See “Micro
Levelers
(Paramount ME II
Only)” on page
108.
Not available.
Not available.
Not available.
Optional Accessories
The table below lists optional accessories for each model.
Optional Accessory
Counterweight Shaft Extension
Bar
8-in. long, 1.875-in.
wide
8-in. long, 1.5-in.
wide
Not available.
Counterweights
14 kg/30 lb.
18 kg/40 lb.
1.875-in. bore
9 kg/20 lb.
4.5 kg/10 lb.
1.5-in. bore
9 kg/20 lb.
4.5 kg/10 lb.
1.5-in. bore
Software Bisque Permanent Pier
48V 5AH Portable Power Supply
Power supply cables to use in
conjunction with the mount’s
built-in through the mount
power cabling (page 177)
Base to Pier Adaptor Plate for
mounting the Paramount to an
existing pier
Polar alignment scope, mounting
hardware, and cover
Not available.
Pyramid™ Portable Pier
Not available.
Paramount Mighty Tripod
Not available.
Not available.

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Optional Accessory
Latitude Adjustment Wedge for
use below 10 degrees and above
about 64 degrees latitude
WiSky Wi-Fi Control
Absolute Encoders
Not available.
Not available.
Versa-Plate Spacers
Not available.
Not available.
Optional Software Add Ons and Databases
TheSkyX Professional Edition offers additional software Add Ons and astronomical databases.
For imaging system’s housed inside an automated astronomical dome, consider the optional
TheSkyX Professional Edition Dome Add On (http://www.bisque.com/dome) to automatically keep
the dome aligned to, and track with the mount. (The Dome Add On is included with all Paramount
ME IIs shipped after January 2015.)
TheSkyX Professional Edition Database Add On (http://www.bisque.com/DatabaseAddOn) offers
over 200 GB of astronomical catalogs.
Getting Help
If you have questions about your Paramount, please first carefully review the information in this
document. If you still cannot find an answer, please join the Software Bisque at www.bisque.com/support
and click the Write a New Post link on the Paramount ME II Support Forum
(http://www.bisque.com/sc/forums/114.aspx), the Paramount MX/MX+ Support Forum
(http://www.bisque.com/sc/forums/96.aspx), or the Paramount MYT Support Forum to ask your
question. The Software Bisque monitors this forum between 9 a.m. to 4 p.m. Mountain Time Monday-
Friday and tries to respond to questions within 5 business days (usually faster). Other knowledgeable
community members are there to help outside regular office hours.
What You Need to Know
Successful operation of a Paramount requires a solid understanding of many basic astronomy concepts, a
familiarity with operating a GEM, as well as an understanding TheSkyX Professional Edition.
If you are new to the Paramount, operating a GEM, or just getting into astronomy, please peruse the
following section. Based on years of support feedback, even experienced observers often do not
understand fundamental concepts as they relate to operating a Paramount.

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What are the differences between right ascension, azimuth and hour angle?
Why does the meridian matter when operating a GEM?
What exactly is synchronization?
What is homing and what does it actually do?
What is mount parking?
How does atmospheric refraction affect mount performance?
Why is polar alignment so important?
In addition to these basic questions, if you have never controlled a robotic GEM with TheSkyX Professional
Edition, please carefully read the following sections and then use TheSkyX Professional Edition’s Telescope
Simulator feature before setting up, connecting to, and operating the Paramount.
Coordinate Systems
The three most common coordinate systems used when working with equatorial mountings are described
below. Making sure you understand the differences between each system now will really help
troubleshooting issues in the future.
The Horizon Coordinate System
The horizon or “horizontal” coordinate system is used to specify the position of celestial objects relative
to the local horizon.
Figure 1: The horizon-based altitude and azimuth coordinate system.
Altitude
The altitude (alt) of an object is expressed as the number of degrees from the horizon (the ground at a
far distance) to the object, and is always between minus 90 and plus 90 degrees. Objects that have a

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negative altitude are below the horizon. For example, the Sun just after sunrise is close to the horizon so
it has an altitude of a couple of degrees, and just after sunset its altitude is minus one or two degrees.
Azimuth
The azimuth (az) of an object is generally reckoned from North, increasing in the clockwise direction, and
ranges from 0 to 359 degrees. North is 0 degrees, east is 90 degrees, south is 180 degrees and west is 270
degrees.
When the Paramount is controlled by TheSkyX Professional Edition, attempting to slew the mount below
the local horizon is not permitted and will result in an error message.
The Equatorial Coordinate System
The horizon coordinate system is not convenient for specifying the location of celestial objects because
the horizon coordinates of stars and other objects are continuously changing with time (due to the
rotation of the Earth).
The exception occurs with objects near the north and south celestial poles. These positions are unique
since they are near to the axis of rotation of the Earth and therefore move only in small circular paths.
Polaris, the North Star, for example, remains at a nearly constant altitude and azimuth. In the equatorial
coordinate system, the coordinates of all celestial objects remain fixed* from hour-to-hour, day-to-day
and so on.
An object's equatorial coordinates remain the same regardless of from where on Earth the object is
viewed. This allows astronomers to create star maps that apply to any place on Earth, or publish the
anticipated position of an upcoming comet so that astronomers everywhere know where it is located
among the stars.
The equatorial coordinate system used to specify the positions of celestial objects is directly analogous to
the latitude-longitude coordinate system used on Earth. In fact, if you were to expand the latitude and
longitude grid of the Earth so that it is out beyond all stars, you would have a sphere with identical
geometry to the celestial sphere.
We suppose that all stars and deep-sky objects are located on a very large sphere (out beyond all stars).
We call this the celestial sphere. For purposes of describing the positions of celestial objects, we consider
all stars and deep sky objects to be on the celestial sphere, when actually they are all positioned at varying
distances from the Earth.
* Equatorial coordinates change over long periods of time due to precession (wobbling of the Earth).
TheSkyX computes this change in stars’position for the current date. Precession, however, does not
change the relative positions of objects with respect to one another.

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Right Ascension
The geometry of the right ascension (RA) lines on the celestial sphere is the same as the longitude lines
on Earth. Longitude lines divide the Earth into 360 degrees. Right ascension lines divide the celestial
sphere into 24 hours, based on one revolution of Earth. Therefore one hour of right ascension equals 15
degrees (360 divided by 24). See the definition of Local Sidereal Time for additional information on why
24 hours are used for right ascension instead of 360 degrees.
Zero degrees longitude passes through Greenwich, England and is the designated reference line for
longitude. What, then, is the reference line for zero hour’s right ascension? Astronomers use the vernal
equinox, the location where the Sun crosses the celestial equator during its apparent annual motion
against the background stars, as a "starting point" for right ascension.
The term "right ascension" comes from the fact that when viewed from the equator, all stars rise (or
ascend) at right angles to the horizon, so their times of rising are called their times of right ascension.
Figure 2: Right ascension and declination relative to the celestial sphere.
Declination
The declination (dec) lines on the celestial sphere are similar to latitude lines on Earth, ranging from –90
degrees to +90 degrees. The “declination” of an object is the angle measured from the celestial equator
(0 degrees declination) along a meridian line through the object. Polaris, the North Star has a declination
of just over 89 degrees so it is very close to the north celestial pole.
Hour Angle
Hour angle (HA) is measured from the meridian westward, along the celestial equator and uses the same
units as right ascension (hours, minutes, and seconds). A celestial object on the meridian is located at
hour angle 0. Six hours of time later, the object is located at hour angle +6. Twelve hours later, when the
object rises, its hour angle is –6 h.

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Hour angle can be used to describe a telescope’s mechanical orientation with respect to a horizon-based
hemisphere. For Paramount mounts with AutoHoming™, when the mount finds home, the home position
is a fixed, mechanical mount orientation. In the northern hemisphere, when homing is successful, the
mount always points to hour angle 2 and declination 0.
Smaller hour angles equate to positions of optimal observing, so your telescope will probably spend a
great deal of the time pointing to and tracking objects near hour angle zero (or, near the meridian).
Note that TheSkyX Professional Edition can be used to configure the Paramount’s “flip hour angle” (page
122) in order to maximize the length of time an object can be tracked past the meridian.
Local Sidereal Time
Local sidereal time (LST) is always equal to the instantaneous right ascension of the local meridian. When
you know the LST, you can look at star maps and determine which objects are near the meridian (those
with a right ascension close to the LST). For example, if the LST is 6:10:00, this means that stars with a
right ascension of about 6 hours are visible along the meridian.
If everyone reckoned time based on the Sun crossing the meridian, then each longitude on earth would
have a different time of day. That means noon, or the time the Sun crosses the meridian, would come a
few minutes earlier for someone living 60 miles to the east. Only those people living at the same longitude
would share a common time.
In the late 1800’s time zones were established to minimize the problem of having different time in
populous regions. The time within these zones is called zone time. Zone time places all locations on Earth
into various time zones. By definition, time zone zero is at zero degrees longitude, and the time zone
increases by one hour every 15 degrees longitude moving east, or decreases by one hour moving west.
The Paramount relies on TheSkyX Professional Edition having the correct time zone for your observing
site. When TheSkyX Professional Edition’s time zone is not correct, the position of the telescope cross
hairs will be offset by the time zone hour error when viewing horizon-based Sky Charts.
Atmospheric Refraction
The effects of atmospheric refraction on the position of celestial objects, as well as its effect on the
sidereal tracking rate, are often overlooked or even ignored by many amateur astronomers.
The refraction nuisance (and other system errors like tube flexure) means the “sidereal tracking rate” is
simply not good enough to precisely track objects. Refraction also displaces the position of the celestial
pole and makes precise polar alignment more difficult.
Some other interesting and significant facts about how refraction affects an object’s apparent position
include:
For a sea-level site, the refraction at 45 degrees zenith distance (ZD) is about 60 arcseconds (one
arcminute).

Paramount User Guide
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Except low down in the sky, the refraction goes roughly as the tangent to ZD, so at ZD = 70 degrees,
or, at 20 degrees above the horizon, it is up to 165 arcseconds. (It reaches a 1800 arcseconds, or
0.5 degrees at the horizon.)
Refraction is proportional to pressure, so at high-altitude sites the refraction comes down
significantly. For example at Mauna Kea, 4,205 meters above sea level, the refraction is about 60
percent of the sea level amount.
Refraction is roughly inversely proportional to absolute temperature, so at –5C the refraction is
about 10 percent more than at 20C.
Humidity has little effect in the optical, though it matters a lot at radio wavelengths.
The color of the observed object matters, blue being refracted a few arcseconds more than red
at ZD 70.
When you use your Paramount to take long, unguided exposures at modest or longer focal lengths,
refraction becomes an important source of tracking error that is not taken into account in the standard
sidereal tracking rate.
TPoint can be employed to take care of the atmospheric refraction details for you.
TPoint’s Super Model feature and Polar Alignment Report automatically determines the position
of the refracted pole and give recommendations on how to proceed, including how much to rotate
the altitude and azimuth knobs when adjustment is necessary.
It accounts for and applies refraction when acquiring telescope calibration data as well as corrects
the telescope’s position when the mount is slewed.
TPoint’s ProTrack™feature can be used to apply tracking corrections to the mount based on the
point calibration data.
Polar Alignment Basics
For optimal performance, the equatorial axis of a GEM must be aligned to the refracted pole
to within 100 arcseconds.
If the mount’s equatorial axis is not “closely” aligned with the celestial pole…
Stars will drift in of the field of view, mostly in declination; quickly when polar
alignment is particularly poor.
When you tell TheSkyX Professional Edition where the mount is pointing, through a
process called “synchronization” (page 25), the synchronization results will be
incorrect, or “skewed” by the amount of the polar alignment error. For example, if
the polar axis is ten degrees “low” in altitude, then the resulting synchronization
positions computed by TheSkyX Professional Edition will be off by this same amount
in declination. The result is that the mount will not point with any accuracy or
repeatability.