The following is a subset of the commands (#hashtags) and options supported by the observatory's Mastodon, Text MessagingEmail, and the Communicator App interface. See the Command Reference (Advanced) and Processing Command Reference pages for the complete list of commands and options.

When you send a command via a Mastodon post, be sure to include in the message so that the observatory is notified of your message by Mastodon.

Except for the #help, #hello and #human commands, more than one command can be included in a single Mastodon Post, Mastodon Direct Message, Facebook Messenger message, SMS text, or the body text of an email. Only one command is processed by Communicator App messages.

Some commands need additional information (parameters) in the form of xxx=yyy. If yyy needs to include spaces, surround the entire parameter in double-quotes (eg. "parameter=this is a parameter value". Anything other than a hashtag or parameter is ignored.


This sends a message which directs you to this website. If this command is received, any others are ignored. This command can be used even if you are not an authorized observer.


This sends your message to a human by email - include what you need help on within the message. If this command is received, any others are ignored. This command can be used even if you are not an authorized observer.


This is a good "test" message - the observatory replies by introducing itself! If this command is received, any others are ignored. This command can be used even if you are not an authorized observer.


This command requests the telescope take an image of an astronomical object. The request is placed in the telescope's observation queue. Certain checks are done before the request is accepted. In particular:

  • The object must be observable from Nova Scotia within the next month's time.
  • Most users are limited to having 3 observations in the queue at a time. Users given special permission may have up to 15 observations in the queue.
  • You can't request the same object twice (unless using a different filter or exposure). An exception is made for special observations and solar system objects.

The parameters accepted are as follows:


objectname is required and must be the name or catalog number of an astronomical object (without any spaces). The telescope knows how to find lots of celestial objects, including:

  • The Messier Catalog - a list of bright star clusters, nebulae and galaxies (eg. M1 or M33)
  • Common object names (eg. OrionNebula, ClownFaceNebula, etc.)
  • Any object in the Saguaro Astronomy Club Deep Sky Database. This includes about 10,000 bright star clusters, nebulae and galaxies. Specify the object's catalog number (most off these will be an NGC
  • Any galaxy in the Principle Galaxy Catalog (eg. PGC65086)
  • Stars (by their common name (eg. Vega), or by their HD, HR, SAO, HIP, TYC, GSC, or USNOA2 catalog number). Stars brighter than magnitude 6.5 are not allowed.
  • Variable Stars - any star in the General Catalog of Variable Stars (eg. ZLeo or V0456Cyg)
  • Double Stars - any star in the Washington Visual Double Star catalog (eg. STF2578)
  • Planets (by their name) - note that planets will not look that good as we are all used to seeing planet images taken with space probes!
  • Moon - use 'Moon' as the name. Because the Moon is too bright, it will not be imaged when its phase is close to full. 
  • Comets - any comet presently considered observable by the IAU. Use their full name or their shortened designation (eg. "C/1997B1" or "125P")
  • Asteroids - any "numbered" asteroid (also called minor planets) brighter than about 18th magnitude (that usually means 1000s of them!). Use their proper name (eg. "Vesta") or their number designation (eg. "(94)" which is Aurora) 


This adds your comment to the observation. If more than one word is needed, enclose the whole parameter in double-quotes (eg. "comment=Andromeda Galaxy"). As an example of how it might be used, you might use this feature to give another name for your request or the reason for the request.


This specifies the exposure time, in seconds, for the observation. It is optional - if left out 180 seconds (3 minutes) is used for brighter object types and 300 seconds is used for fainter object types (galaxies, nebulae, etc.). The shortest values accepted are 0.1 seconds and the longest is 300 seconds (5 minutes). When the telescope takes the image, it actually splits the exposure into parts 60 seconds or less and automatically combines the parts into one image before it is sent to you. Users given special permission are allowed up to 900 seconds (15 minutes).

For some bright objects (the Moon and the planets) the specified exposure is overridden to hopefully provided better images for these objects.


This specifies which colour filter is placed in front of the camera. It is optional - if left out, the CLR filter is used (this is clear or un-filtered). Our camera takes black and white images - colour images are made by combining separate images taken in red, green and blue filters. The valid filter names are here. See this FAQ for more information about choosing an appropriate filter.

fullsize=yes (or no)

This is optional and when set to 'yes' causes the image to cover the largest sky area possible for the camera used. The default size, which fits most common objects, is smaller.

If non-recognized parameters are present, they are ignored. If an error is detected, you will receive reply message indicating the nature of the error, otherwise you will receive a reply like:

Object M42 is in my #request queue as ID 2354 (exposure=180 seconds filter=HA)

Note the ID (2354 in this case) - that is the request ID assigned uniquely to your observation request.

Here are some examples:

#request object=M36

Requests an observation of star cluster M36 (exposure time would be default of 3 minutes and unfiltered (the "LUM" filter) with normal image size)

#request object=NGC7331 exposure=300

Requests an observation of galaxy NGC7331 (exposure time would be 300 seconds and normal image size)

#request object=M27 filter=OIII exposure=30

Requests an observation of planetary nebula M27 (exposure time would be 30 seconds using the Oxygen III filter and normal image size)

#request object=M42 filter=HA fullsize=yes

Requests an observation of nebula M42 (exposure time would be default of 3 minutes using the Hydrogen Alpha filter and full image size)


This command sends you the number of requests in observation queue and a link to web page showing your requests. An example reply is shown below.

You have 2 requests in the queue. The details are here:


This command deletes one of your requests from the observation queue. The request ID is to be provided as in the following example:

#delete id=00005

You can only delete your own requests. If you don't know the ID, use the #myrequests command.


This command queries the telescope's object database. If found, it also determines whether or not the object can be observed in the near future, and therefore be used by the #request command.

The parameters accepted are as follows:


objectname is the name of the object you wish to search for.

Here is an example:

#lookup object=BGO-2-UMASN1

An example reply is:

Fixed object BGO-2-UMASN1 found at position RA=05:32:02.6 DEC=+82d02'18", and it can be requested now.


Use this command to renew your observer account. Accounts typically expire after one year.

Here is an example:

Please #renew my account. I need it to continue my research.

An example reply is:

A human will review your request and get back to you.


Use this command to set or change your observer account password. Passwords are used to authenticate the Communicator app and an observatory web-app that is currently under development.

The required parameter is as follows:


The password must be 7-20 characters long. Do not use a password that you use for other important accounts, as we cannot guarantee its security. Do not set the password using a public medium such as a public Mastodon post, or it will be exposed publicly!

Here is an example:

#password pw=iloveastronomy12

An example reply is:

Your password has been updated.


This command returns your name, observer ID, assigned observer group, and a web link providing more info about your observer account.

Here is an example:


An example reply is:

You are 'Tiffany Fields' (ID=1356) in the 'Manager' observer group. Your account does not expire. More info: