ASTRO DEVICES Nexus DSC User manual

Nexus DSC
USER MANUAL
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User Manual for Nexus DSC
Version 2.2
Firmware version 1.x.x
Last revised on January 24th, 2017
Printed in Australia
Copyright
Copyright © 2014-2017, Astro Devices. All rights reserved.
No part of this manual may be reproduced or transmitted in any form for any purpose other than
the purchaser’s personal use, without the express written permission of Astro Devices.
Astro Devices reserves the right to make changes and improvements to its product without
providing a notice.
Precautions and Safety
Electricity
Nexus DSC contains a rechargeable Lithium-ion battery. Lithium-ion
batteries can explode or cause a fire if they are used incorrectly or if they
are defective. Therefore, you are recommended to read the following
instructions very carefully:
NEVER leave Nexus DSC where it is subjected to extremes in temperatures. This
includes low levels as well as high.
DO NOT leave Nexus DSC where it is in direct sunlight or in an enclosed space,
such as a car, that can become extremely hot very rapidly.
Do not drop or subject the Nexus DSC to impact.
Use only approved power adapter to charge your Nexus DSC.
Do not handle power plug and adapter with wet hands. Electrical shock may
result. Immediately power off the product and unplug the DC adapter and/or
batteries if smoke or odours emit from the product. Immediately power off the
product and unplug the DC adapter if water or other liquids are present.
Product
Keep it away from harsh environments including humid, dusty, and smoky
areas.
Do not use excessive force on the connectors.
Do not attempt to disassemble the device without prior consultation with Astro
Devices.
Do not place heavy objects on the product. Damage to your products may result
from improper use.
Technical Support
Astro Devices
198 The Esplanade,
SYLVANIA, NSW 2224
AUSTRALIA
ABN 75 270 616 917
E-Mail: [e-mail]
Website: http://www.astrodevices.com

Nexus DSC User Manual
Thank You!
Thank you for purchasing Nexus DSC digital setting circles telescope computer. We hope you
enjoy it!
You have purchased one of the most advanced Digital Setting Circles computers. It will allow you
to located celestial objects quickly and easily. Nexus DSC has a huge database of objects –
planets, galaxies, star clusters, globular clusters, nebulae and others. It also provides extensive
descriptions for those objects – magnitudes, sizes, common names, alternative designators,
surface brightness, separations for double stars, spectral class, galaxy morphology. It is all
available at a press of a button!
This user manual will get you started and help you make the most of your Nexus DSC.

Nexus DSC User Manual
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Nexus DSC User Manual
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TABLE of CONTENTS!
TABLE&of&CONTENTS!...................................................!1!
Introduction!.................................................................!2!
Product!Features!........................................................!2!
Technical!specifications!......................................................!2!
Digital!setting!circles!specifications!....................................!2!
Package!Content!................................................................!2!
Introduction!.................................................................!3!
Unpacking!...........................................................................!3!
Controls!..............................................................................!3!
Charge!the!battery!.............................................................!3!
User!interface!.....................................................................!4!
Main%menu%.....................................................................%4!
Status%Bar%.......................................................................%4!
Keypad%...........................................................................%4!
Initial!Setup!........................................................................!4!
Setting%the%time%and%date%..............................................%4!
Connecting%to%your%telescope%.........................................%5!
Telescope%Settings%..........................................................%5!
Two%star%alignment%........................................................%6!
Alignment%object%screen%.................................................%7!
Pointing%accuracy%...........................................................%7!
Locating%an%object%..........................................................%8!
Improving%pointing%accuracy%..........................................%9!
Nexus!DSC’s!menus!.....................................................!9!
Settings!...............................................................................!9!
Telescope%.......................................................................%9!
Other%Parameters%........................................................%10!
Communications%..........................................................%10!
Time%and%Date%..............................................................%11!
WiFi%..............................................................................%11!
Display/Keypad%............................................................%12!
Align!.................................................................................!12!
Altitude%Reference%........................................................%12!
First%Object%Alignment%.................................................%13!
Second%Object%Alignment%.............................................%13!
Alignment%Status%..........................................................%13!
Mpoint%Start%.................................................................%13!
Mpoint%Parameters%......................................................%14!
Mpoint%Edit%Points%........................................................%15!
Mpoint%Analyse%............................................................%16!
Equatorial%Timer%..........................................................%16!
Find!...................................................................................!17!
From%Catalogues%..........................................................%17!
From%Observation%List%..................................................%19!
Object%at%RA/Dec%..........................................................%20!
From%Planetarium%........................................................%20!
Identify!.............................................................................!21!
Tour!..................................................................................!22!
Test!...................................................................................!22!
Encoders%.......................................................................%22!
WiFi%..............................................................................%22!
USB%...............................................................................%23!
Serial%............................................................................%23!
Utilities!.............................................................................!23!
Update%Catalogues%from%microSD%................................%23!
Info!...................................................................................!24!
About%Nexus%DSC%..........................................................%24!
Time%.............................................................................%24!
Battery%.........................................................................%24!
GPS%...............................................................................%25!
Advanced!Topics!......................................................!25!
Daylight!Testing!................................................................!25!
Firmware!Update!.....................................................!25!
Apendix!.......................................................................!26!
Ports!Pinouts!....................................................................!26!
Serial!Port!.........................................................................!26!
Encoders!Port!...................................................................!26!
List!of!Compatible!Planetarium!Software!........................!27!
FREQUENTLY!ASKED!QUESTIONS!(FAQ)!...........................!27!
Troubleshooting!......................................................!27!
Warranty!....................................................................!29!
Technical!Support!...................................................!29!

Nexus DSC User Manual
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Introduction
Nexus DSC is a digital setting circles computer
with optional WiFi interface for your telescope. It
works with most popular telescopes – on
equatorial or Alt-Azimuth mounts.
Nexus DSC is a very sophisticated device for
locating celestial object in the sky. Only two rotary
encoders are required to be fitted to your
telescope in order to be able to locate celestial
object with Nexus DSC.
Product Features
Below is a short outline of main features of your
Nexus DSC.
Technical specifications
• CPU – 32 bit, MIPS 4K running at 80MHz
• Memory – 16MB internal FLASH
• External memory – up to 64GB on micro SD card
• 3.12” Red OLED screen (256x64 pixels) with 256
levels of brightness
• Full numeric keypad with adjustable back light
• Real time clock with thermal compensation
• Built-in GPS receiver with support for GPS and
GLONASS
• Built-in 5000mAh rechargeable Lithium battery
• Operating temperature range from -20 oC to +50 oC (-
5 oF to +120 oF)
• Humidity 10%-90% non-condensing
• Optional WiFi interface
• FCC / CE/ IC certified 2.4GHz IEEE 802.11b/g
transceiver
o Supports Access Point and infrastructure WiFi
networks
o Secure Wi-Fi authentication schemes
o Class I WiFi device (up to 150 meters)
o Uses 2412 ~ 2484MHz Unlicensed ISM band
(channels 1-14)
o Output power 0.08W
• One RS232 port
• One USB port
• Upgradeable firmware and catalogues (firmware is
upgraded using a USB memory stick)
• Can be charged/powered by an external power
source of 5-16V DC; can be charged from a cigarette
lighter socket in a car
• Reverse polarity protection
• RoHS compliant
• Size: 140 x 120 x 30mm (5.5” x 4.7” x 1.2”)
• Weight: 260g (9oz)
Digital setting circles specifications
• Intuitive graphical user interface
• Supports Alt-Az mounts, Equatorial Mounts, Equatorial
Platforms
• Supports a two star alignment
• Filter objects by magnitude, constellation and object
type
• Displayed angular resolution is 0.01 of a degree
• Internal FLASH memory contains a database of more
than 73500 objects:
o Named stars
o Bright stars, Flamsteed, Bayer, Asterisms
o Planets, Sun, Moon
o Common named objects
o Full catalogues: Abell Galaxy Clusters, Abell
Planetaries, Arakelian, Arp Peculiar Galaxies,
Barnard, Caldwell, Collinder, ESO, Herschel,
Hickson Compact Groups, King, LBN, Markarian
galaxies, Messier, Minkowski planetaries, IC, NGC,
Palomar Globulars, PK, PN, Sharpless, Stock,
Terzan, Trumpler, UGC
o
• Around 1.9 million objects are located on optional
microSD card
o Comets and Asteroids (updatable from the MPC)
o HyperLEDA catalogue
o MCG, SAO
o Full Washington Double Stars catalogue
• Displays object’s information: magnitude, size, surface
brightness, spectral class, double star separations,
galaxies morphology, alternative names , rise time, set
time, transit time etc.
• Identify function; can also display up to 128 nearby
objects
• Tour modes: within a radius and within a constellation
• Supports a multi point telescope pointing analysis
system for telescope pointing corrections
• Supports rotary encoders with up to 999999 steps per
revolution
• Shows internal battery status – remaining capacity,
current power consumption and percentage of charge
remaining
• Can be interfaced to a tablet/smartphone/computer
using a standard RS232 interface or optional WiFi
interface
• Internal real-time clock can be synchronised with GPS
time automatically
• Time display of local time, UTC and local sidereal time
• Supports LX200 emulation
• Supports ServoCAT, SiTech and SkyTracker motor
controllers
Package Content
The package contains:
• Nexus DSC
• User manual
• DC 2.1mm to cigarette lighter power cable
• USB to DC 2.1mm cable (for charging only)
• Optional serial cable
• Optional power adapter 6V, 3A, 90-264V
AC

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Introduction
Unpacking
Nexus DSC has a protective film covering the front
panel. Please peel it off to be able to see the
display clearly.
Controls
All controls are situated on front panel of Nexus
DSC:
– power switch
– keypad
– display
– external power connector (DC 2.1mm)
– charging status LED
– USB connector
– Serial (RS232) port
– Encoders port
– Micro SD socket
is used to charge the battery; can be
connected to a power adapter or to a cigarette
lighter socket (using the supplied cable)
indicates the charging status of the battery
Blinking
type
Description
Solid ON
The internal battery charging is in
progress
OFF
The internal battery has been fully
charged
Flashing
Flashing LED is indicating an error (power
source is not supplying sufficient voltage
and or current)
The USB port acts as a USB host. It cannot
be used to connect Nexus DSC to a computer
directly.
The USB port on Nexus DSC is used for:
• Firmware updates
• To interface Nexus DSC to ServoCAT
• To interface Nexus DSC to SiTech motor
controller
Serial port is a standard RS232 port, 6P6C
RJ connector. It is used for the following
purposes:
• To connect Nexus DSC to a computer
• To connect Nexus DSC to ServoCAT
• To connect Nexus DSC to SiTech
controller
Encoder port is used to connect encoders
using an 8P8C RJ connector
microSD socket is push-in push-out type
Charge the battery
The battery may not be fully charged at first. It is
advised to fully charge the battery.
Please use either the provided power adapter or
one of the recommended power adapters to
charge the battery.
It is also possible to use the supplied USB to DC
2.1mm cable to charge the battery from a power
adapter with a USB socket. The power adapter
should be capable of supplying at least 1.5A at 5V
otherwise it will take much longer to fully charge
the battery in Nexus DSC.
Connect the power adapter to Nexus DSC and
plug the adapter into a power point.
It is recommended to keep Nexus DSC turned off
during charging to reduce charging time.
WARNING:
Do not connect Nexus DSC to an external
power source that is not within the
specified voltage range. Nexus DSC has
internal over-current protection but it is
safer to use it with the power source
specified.
The internal Lithium battery can only be
charged at a temperature range of 0 oC to
+30 oC (32 oF to 86 oF)
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User interface
Main menu
The main screen consists of a status bar,
horizontal menu with icons and a text description
of the currently selected menu item:
– Status bar
– Main menu
– Menu description
Status Bar
The status bar shows basic information about
battery state, current time, GPS receiver status
and WiFi.
The status bar has the following elements:
WiFi status is only shown if the WiFi is enabled
GPS fix status - the dot in the centre is flashing until the
GPS receiver acquires the current location
Current time in 24 hour format
Battery charge level in %
Keypad
Nexus DSC has a full numeric (0-9) keypad with
directional keys ( , , , ),
and to allow an easy method of control.
The keys have the following functions:
• to keys are used to specify a
numeric information to Nexus DSC
• and keys on the keypad move
between previous and next menu item,
they are also used to move between
control fields (edit value, list, check box,
on-screen buttons) in a dialogue screen.
The key also acts as a backspace
when editing a value in edit fields.
• and keys are used to select an
item from a list, to adjust value in numeric
fields with predefined steps (like ‘Time
Zone’) or to change a character in an edit
field; they can also be used to go to the
previous/next menu level.
• The key activates the selected menu
item (on-screen button press, accepts a
selection from a list, finish editing a text or
numeric value).
• The key goes back to the previous
menu level/screen.
Initial Setup
This section describes how to setup Nexus DSC
to start locating celestial objects. The following
sections will describe all features of Nexus DSC in
detail.
In order to be able to use Nexus DSC for locating
celestial object it is necessary to set a few
parameters first:
• Time and date
• Mount Type
• Encoders’ resolution
Setting the time and date
Please select ‘Settings’ from the main menu:
Then select ‘Time and Date’:
It will show the current time and date that can be
changed:
If all parameters are set correctly then pressing
the key can be used to avoid changing any
parameter.
If the time zone, time and date need to be
changed then and keys can be used to
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select the parameter that needs to be adjusted.
and keys are used to change the value.
Setting the time and date is only required if time
synchronisation with GPS is disabled. However
the time zone and date needs to be set for Nexus
DSC to show the local time correctly.
It usually takes 30 to 60 seconds for the GPS
receiver to get a fix on the location (under
open sky conditions). Nexus DSC will update
the internal real time clock with the time
received by the GPS receiver at this time. The
GPS receiver will automatically be switched
into a power saving mode after it acquired the
location to conserve the battery power.
Connecting to your telescope
Nexus DSC requires only encoders connected to
operate. Please plug the encoder cable into
Encoders port on Nexus DSC.
For operating Nexus DSC with a ServoCAT or
SiTech controller the serial port needs to be
connected to a serial port on ServoCAT or SiTech
controller.
To make sure that encoders are functioning
correctly Nexus DSC has a test mode to test the
encoders. Selecting Test from the main menu
activates it:
Then select Encoders:
will show the current angles and encoder steps:
In order for Nexus DSC to function correctly it is
required to adjust the encoder steps to make sure
that:
• the RA/AZ current position in degrees is
increasing when rotating the telescope
clockwise around RA/AZ axis
• the Dec/Alt current position in degrees is
increasing when moving the telescope up in
declination/altitude
If either of those values is decreasing then set the
encoder steps’ sign for that axis to a negative sign
in the Telescope Settings:
Telescope Settings
Nexus DSC needs the mount type and encoder
steps to be set correctly before it can be used to
locate celestial object precisely.
The mount type and encoder steps are set in the
Telescope Settings that can be accessed by
selecting ‘Setting’ from the main menu:
then by selecting ‘Telescope’:
Then you need to select the telescope:
Nexus DSC allows to have up to five different
telescope configurations. and keys are
used to switch between telescope configurations.
You can also rename TELESCOPE 1 to your
telescope’s name. You just need to activate the
Rename button by using and then press the
key. A text cursor now appears under the
name:
OK

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You will now be able to edit the name and change
it to your telescope name:
Now you need to set other parameters for your
telescope:
where the mount type can be selected by using
and keys. The encoder steps are set to
10000 steps by default and should be set to the
number of steps corresponding to the number of
steps of the encoder installed on your telescope.
Encoder steps can be set by using the numeric
keys on the keypad. Please change the sign in
front of encoder steps for either one or both
encoders if required as described previously:
Two star alignment
Nexus DSC needs to be aligned on two stars
before it can locate celestial objects.
Your telescope does not need to be levelled
for Nexus DSC to locate celestial objects
accurately.
The two star alignment is performed in three
steps.
Please go to the Align menu:
Then select Altitude Reference:
Adjust the altitude reference angle if required:
Now move the telescope into position depending
on the mount type (for 90 degrees reference):
Telescopes on Alt-Azimuth mount should be
positioned vertically:
The same rule applies to telescopes installed on
equatorial platforms. Please note that the
telescope should be at 90 degrees to the ground
board, not the ground.
For equatorial mounts 0 degrees altitude
reference is more convenient.
Telescopes on an Equatorial Fork for a 0 degrees
altitude reference then be positioned as below:

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The telescope does not have to be positioned
exactly at the angle specified, but it should be
within ±10°.
Nexus DSC will automatically switch the screen to
the selection of first alignment object:
While Nexus DSC can be aligned on any object in
its database it is best to use objects form either
Named Stars catalogue or Bright Stars
catalogue.
It is time to select the first alignment object – by
pressing to go to the object selection list and
then using and to change to another
star:
Acamar was selected as it is well above 30
degrees. Now the telescope should be pointed at
Acamar using an eyepiece with a reticle/crosshair
or a very high magnification eyepiece. Press the
button once the telescope is pointing at the
star.
Nexus DSC will now switch to the selection of a
second alignment object:
Please follow the procedure described above to
change the selection of the second alignment
object if necessary.
Press the button once the star is in the
centre of the eyepiece.
Now Nexus DSC will show the alignment error:
Now you can press either the key or the
key to go to the previous menu.
You can go back to align on first or second
object at any time in case the alignment error
is too big.
Alignment object screen
Alignment object screen presents the following
information:
where:
– Currently catalogue
– Currently selected object’s azimuth
– Currently selected object’s RA
– Object’s information
– Currently selected object
– Currently selected object’s altitude
– Telescope’s AZ/RA
– Telescope’s Altitude/Declination
– Currently selected object’s declination
Pointing accuracy
Pointing accuracy depends on a number of
factors:
• Quality of the telescope mount
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• Choice of alignment stars
• Accuracy in pointing on alignment objects
To achieve the best pointing accuracy with an
Altitude-Azimuth mount it is recommended that:
• The alignment stars chosen should always
be at 30 to 80 degrees in altitude and
separated by at least 70 degrees in azimuth.
• Alignment stars should ideally have at least
a few degrees separation in altitude
• Polaris can be used as one of the alignment
stars
To achieve the best pointing accuracy on an
Equatorial mount it is recommended that:
• Polaris should never be used as one of the
alignment stars
• Alignment stars with a declination greater
than 80 degrees should be avoided
• The alignment stars chosen should always
be at 30 to 80 degrees in altitude and
separated by at least 70 degrees in RA.
Locating an object
Once the two star alignment is performed Nexus
DSC can locate celestial object in the sky.
The following steps describe a basic method of
location of celestial objects.
Go to the top menu and select Find:
Select From Catalogues:
Select a catalogue by using the and
keys:
And just leave the Filter as Disable for now:
The display will show the last selected object:
Suppose we would like to find NGC55. Just
press the key and the display will prompt to
continue typing the object number:
Now press the key again and then press
:
Nexus DSC will now show where to move the
telescope to aim at NGC55:
It shows that the telescope needs to be moved
down by 6.9 degrees and counter clockwise by
59.7 degrees. As you start moving the telescope
the numbers will start updating. Continue to move
until both numbers are close to 0s:
If you look through the eyepiece then you will see
NGC55 there now.
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To display additional information about the object
just press or key:
Pressing , or will take you
back to the previous screen.
If a description for the object fits on one
screen then no scroll bar is displayed on
the right.
Improving pointing accuracy
Every telescope has some kind of imperfections.
Nexus DSC supports two methods of improving
pointing accuracy that compensate for those
imperfections: sync objects and Mpoint. Mpoint is
described later in this manual.
Sync objects are used to improve the pointing
accuracy when a telescope is pointing in the
proximity of a synced object. Nexus DSC limits the
number of sync objects to 128. The size of the
area is limited to 10º radius. If there are more than
one sync objects in the area then corrections from
the closest sync objects are used.
Once the two star alignment is performed Nexus
DSC will enable an additional mode to allow
adding sync objects. Use to activate it while
an object from one of the catalogues is selected:
To sync to the object (M79 in this example) and
make sure it is precisely in the centre of the field
of view and of any of offsets are are not exactly 0
then press the key to add it to the sync
objects list. Once you press the key you will
see that offsets became 0s:
Nexus DSC’s menus
Settings
Nexus DSC has a number of parameters that can
be adjusted. All of the adjustable parameters are
stored in non-volatile memory and will be used
every time you turn Nexus DSC on.
Please note that all settings can be reset back
to their default values by turning Nexus DSC
on while holding the key. You will be
asked to confirm the reset to the factory
settings.
Telescope
Nexus DSC needs the mount type and encoder
steps to be set correctly before it can be used to
locate celestial object precisely.
The mount type and encoder steps are set in the
Telescope Settings that can be accessed by
selecting Setting from the main menu:
then by selecting Telescope:
Nexus DSC supports up to five different telescope
configurations. Each telescope configuration has
its own mount type, encoder steps, altitude
reference angle value. Having different telescope
configurations allows you to use Nexus DSC with
different telescopes without spending time on
setting all parameters.
Then you need to select the telescope:
and keys are used to switch between
telescope configurations.
To select a telescope configuration without
changing any parameters just press the
key.
You can also rename TELESCOPE 1 to your
telescope name. You just need to activate the
ESC
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Nexus DSC User Manual
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Rename button by using and then press the
key. A text cursor now appears under the
name:
You will now be able to edit the name and change
it to your telescope name:
Now you need to set other parameters for your
telescope (by pressing the key when the
Adjust button is active):
where the mount type can be selected by using
and keys. The encoder steps are set to
10000 steps by default and should be set to the
number of steps corresponding to the number of
steps installed on your telescope. Encoder steps
can be set by using the numeric keys on the
keypad. Change the sign to negative if required as
described previously:
Nexus DSC has a provision for changing the
default direction of the arrows indicating where to
move the telescope. It can be changed by
selecting REVERSE ARROW:
Other Parameters
The Other Parameters menu is to set other
settings that do not fall under a specific category
for your Nexus DSC.
Altitude limits can be specified that are used for:
• Limiting a range of objects’ search in Tour
modes
• Limiting slewing the telescope when Nexus
DSC is used with a motor controller
(ServoCAT, SiTech, SkyTracker)
Sounds are played during the alignment. Pressing
the Catalogues in Find button will allow you to
select which catalogues to show in the Find
mode.
Precision controls the number of digits displayed
after the decimal point for the offsets to the target
object.
Communications
Communications menu allows to set parameters
for serial port and USB port. Please select
Communications from the Settings menu:
USB
USB port settings are set by selecting the USB
menu:
Nexus DSC supports interfacing to ServoCAT
through the USB port for performing GOTO
commands from a planetarium application. For
third generation of ServoCAT you will need a USB
cable supplied with ServoCAT, for first and
second generation of ServoCAT a USB to serial
adapter is required – the adapter must be based
either on FT232 chipset, on CP210x chipset or on
PL2303 chipset. Please contact Astro Devices for
a list of compatible USB to serial adapters.
OK
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For operating Nexus DSC with ServoCAT it is
necessary to set a few parameters:
• Communication protocol set to ServoCAT
• Baud rate set to 9600
• Stop bits set to 1
• Data bits set to 8
• Parity set to None
Serial
Serial port parameters are set by selecting the
Serial menu:
Now the serial port parameters can be adjusted
as required:
• Communication protocol
• Baud rate
• Stop bits
• Data bits
• Parity
Time and Date
Nexus DSC has a built-in battery backed real time
clock with temperature compensation.
To set the time you need to select Time & Date:
then the time settings can be adjusted:
The easiest method of setting the time and
date parameters is to set TIME ZONE,
Daylight Savings, enable GPSsync and then
step outside to allow the GPS receiver to get
a fix on the location and the time and date will
be set automatically.
WiFi
Nexus DSC’s optional WiFi interface can be
disabled, set to Access Point mode (when Nexus
DSC acts as a WiFi access point thus allowing
other devices to joins its network) or it can be set
to Infrastructure mode (for connecting to an
existing WiFi network). To change various WiFi
parameters can be done by choosing Settings-
>WiFi:
By default the WiFi is disabled.
The easiest way of using Nexus DSC with a
smartphone/tablet/laptop is to switch the WiFi to
Access Point mode:
If default parameters are to be used then after
changing WiFi Mode to Access Point just press
the key until Next button on the screen is
flashing then press key to activate OK button
on the screen and press the key.
Otherwise two other pages allow changing all
available parameters:
OK
OK

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Please note that this password needs to be
at least 8 characters long. If Password is set
to Password (case sensitive) then Nexus
DSC will create an open WiFi network.
Display/Keypad
Nexus DSC allows you to adjust the brightness of
display and of the keys’ backlight. The display
brightness has a range from 0 to 31 (31 is the
maximum) while the back light has a range from 0
to 100 (0 will turn the back light off while 100 is the
maximum level).
To adjust the levels of brightness is access
through Display/Keypad:
which bring up the controls:
Use and keys to switch between
Display and Keypad and and keys to
adjust the levels.
Once you have adjusted the brightness levels to
the ones you desire move to OK button on the
screen and press the key to save them.
Align
Align menu contains all functions handling the
telescope alignment:
• Altitude reference alignment
• First object alignment
• Second object alignment
• Alignment status
• Mpoint start
• Mpoint parameters
• Mpoint analyse
• Equatorial platform timer
All alignment functions are accessed by selecting
Align from the top level menu:
Altitude Reference
The first step of the telescope alignment is to set
the initial altitude reference.
It is done by selecting Altitude Reference from
the Align menu:
Now you can select the initial altitude reference
angle:
The are three choices with the angle:
• 90°
• 0°
• Custom
The custom angle can be set with a precision of
1/100 of a degree. Once Custom is selected you
can change the integer part (from -180° to +180°)
using and keys:
OK
!

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13
And then you can set the fractional part using
and keys:
First Object Alignment
You can choose first alignment object by selecting
First object alignment from the Align menu:
Use and keys to activate a selection list
for the catalogue (CAT) and a selection list for
objects (OBJ). Use and keys to change
the selection.
Aim the telescope at the selected object using an
eyepiece with a reticle or a high magnification
eyepiece and once the object is in the centre
press key:
Nexus DSC will automatically switch to the
Second object alignment.
Second Object Alignment
You can choose first alignment object by selecting
Second object alignment from the Align menu if
Nexus DSC did not activate it automatically – for
example, if you decided that the telescope was not
aimed at the second alignment object precisely.
Please repeat the procedure describe above for
the second alignment:
Nexus DSC will store your selection of
alignment catalogues and objects in non-
volatile memory which means that you don’t
need to change the selection next time you
observe.
Alignment Status
The alignment status shows whether the two star
alignment was successful (it will show the error if
unsuccessful) and how accurate the alignment
was achieved (in degrees). Any value in range -
0.0 to 0.5 is good for visual observing – the
smaller the value the better.
Mpoint Start
Every telescope has some kind of imperfections:
• Fabrication errors
• Mechanical and optical axes not being
perpendicular
• Flexure of telescope mechanical structure
Nexus DSC can compensate for most of
systematic errors.
Mpoint calculates a mathematical model of your
telescope and performs pointing corrections in
real time.
Using Mpoint telescope pointing correction
involves:
1. Performing the initial two star alignment
2. Starting an Mpoint run of calibration objects
(from 4 to 128 objects)
3. Analysing the results
4. Enabling the model to be used for pointing
corrections
The first step has been described earlier. The
second steps starts with selecting Mpoint Start
from the Align menu:
Then you can select a catalogue of objects to be
used as calibration objects:
OK

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14
It is always better to use either Named Stars
catalogue or Bright Stars catalogue for calibration
objects as it is much easier to put stars in centre
of eyepiece. It is best to use an eyepiece with a
reticle for the calibration run to achieve the precise
pointing of the telescope at calibration objects. It
is also advisable to use stars that are currently at
30° to 80° in altitude (the current altitude is
displayed in square brackets at the bottom of the
screen).
Once you selected a catalogue you can start the
calibration run:
The screen shows you where to move the
telescope to Ankaa in this example. Move move
the telescope and put the star in the centre of your
eyepiece as precise as possible:
Now press the key. You will see that the
counter at the bottom of the screen (after the
closing square bracket) has been incremented
and became 3:
Now continue the calibration run until you collect
enough calibration stars:
Calibration stars are automatically added to
sync objects list and Nexus DSC will apply
the correction to pointing immediately and
the offsets will become equal zero;
It is always good to have the calibration stars
spread across the whole sky for achieving the best
results.
Adding calibration stars in Find/Identify/Tour
modes
It is also possible to add calibration stars in
Find/Identify/Tour modes. The two star alignment
needs to be performed before adding calibration
stars for MPoint analysis.
For example, in Find mode when Acrux is shown
and the telescope has it in the centre of the field
of view:
Pressing the key will display the following
screen:
The current object will be added for the analysis:
The same procedure is used in Identify and Tour
modes. The screen will show:
Pressing the key will display the following
screen:
Mpoint Parameters
Once you performed the calibration run on a good
number of stars (>7) you can select which errors
OK

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15
you would like to account for. There is a
mathematical formula associated with each error
and it is referred to as a term. You can select
which terms to use for your telescope model by
selecting Mpoint Parameters from the Align
menu:
Use and keys to choose a check box
for a term. Use and keys to
enable/disable the term.
The bottom left corner of the screen show a page
number of terms. There are currently 19 terms
spread over 4 pages.
Activate the Next button and press key to
go to the next page:
Term
Mount
Type
Description
RA Offset
All
IA (AZ offset for AltAz)
RA Scale
All
Usually equal 1
Dec Offset
All
IE (Alt offset for AltAz)
Dec Scale
All
Usually equal 1
Tube
Square
AltAz
or Collimation error:
for Alt/Azimuth
mounts it is non
Term
Mount
Type
Description
perpendicularity
between pointing
direction and altitude
axis.
Mount
Square
EQ
Non-perpendicular
error - in equatorial
mount if the RA and
Declination axes are
not perpendicular.
NPAE
AltAz
non perpendicular
axis error
PAxis NS
AltAz
Azimuth Axis
Misalignment North-
South (AN)
PAxis EW
AltAz
Azimuth Axis
Misalignment East-
West (AW)
Tube
Flexure
AltAz
Tube Flexure (TF)
Fork Flexure
EQ
For fork mounts -
the flexure in fork
arms
DEC Axis
Flexure
EQ
Declination Axis
flexure (DAF)
RA Sine
All
AZ Sine for AltAz
(HCES)
RA Cosine
All
(HCEC)
Dec Sine
All
(DCES)
Dec Cosine
All
(DCEC)
Mount
Square Sine
EQ
PAxis NS
Sine
EQ
Polar Axis North-
South Misalignment
Sine
PAxis NS
Cosine
EQ
Polar Axis North-
South Misalignment
Cosine
The terms above are in the order of significance.
Mpoint Edit Points
Once the telescope is aligned on a number of
objects you can check how they errors are
distributed in relation to the average centre. To
see all alignment objects' error distribution you
need to select Mpoint Edit Points:
OK

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This screen shows a diagram that has pointing
errors shown as dots relative to the centre point:
The first line on the right shows the pointing type,
next line shows the current point (object) and the
last line shows the object name.
You can switch between Raw Pointing errors
(uncorrected pointing without the pointing model)
and Corrected pointing by using and
keys. To go to next/previous point use and
keys. To delete a point press key.
Mpoint Analyse
Once you aligned your telescope on a reasonable
number of calibration stars and selected terms
that you want to use for your telescope’s model
you can analyse the results. Select Mpoint
Analyse from the Align menu:
The screen will show a diagram for two modes –
Raw Pointing (without the model) and Corrected
Pointing (when using the model calculated). You
can switch between them by using and
keys:
If you the results are suitable then you can enable
using the calculated model for telescope pointing:
If you wish to adjust the model then you can:
• Add more calibration stars
• Add or delete which terms are used for the
model
If you did not align on a sufficient number of
calibration stars then the following error message
will be displayed:
Equatorial Timer
Equatorial Timer is intended to be used when
Nexus DSC is operated with a telescope mounted
on an equatorial platform.
Once you performed the two star alignment (with
the platform in its starting but stopped position)
you need to start the equatorial platform and the
equatorial timer at the same time. You can access
the timer control by selecting EQ Platform Timer
from the Align menu:
Then activate the Start button using use key:
And press the key and start the equatorial
table at the same time. You will see that the timer
starts incrementing:
0
OK