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Bright Star Monitor Section

Welcome to the AAVSO BSM Section page

Administrator: David Cowall       Contact

Science Advisor: Arne Henden

System Software Advisor: George Silvis

System Technical Advisor: Ken Menzies


Interested in joining this section? Click Here for instructions.

What is the Bright Star Monitor Section?


The purpose of the BSM Section is to provide members with observational resources and encouragement to perform research, prepare scientific papers, and enhance their photometry skills. It supports the AAVSO Mission of global observing, promoting science research and public outreach by offering members an opportunity to:

  • Conduct CCD/CMOS photometry

  • Image variable stars beyond the reach of personal equipment

  • Write a paper or contribute to a JAAVSO article with quality data

  • Facilitate member and public outreach educational projects

  • Image targets requiring global cadence coverage

  • Support AAVSO Alerts and Campaigns with the professional community

  • Avoid poor user site seasonal observing conditions

This website provides the member a description of the BSM equipment and processes, useful URL links, and help to propose and conduct successful projects.

BSM Section membership:

You can become an active member by following the BSM Section page and subscribing to the AAVSOnet forum. The forum offers members a place to follow current events, BSM Section technical discussions and a clearinghouse for observing projects that will attract professional contribution and collaboration. Would you like to help manage the BSM Section, make your interest known and/or view forum posts for requests for help!

BSM Sites:

The AAVSO Bright Star Monitor telescopes are a subset of the larger AAVSOnet network which are located at sites around the world. Each BSM site is equipped with a small refractor, a high grade astronomical camera (SBIG CCD / ZWO CMOS) and standard Astrodon photometric filters.  They are operated robotically and are locally supported by AAVSO member volunteers.  Each telescope can perform precise photometric measurements of the sky’s relatively bright stars, those in the range of 3 to 13 V magnitude. It is free to use by all AAVSO members.


BSM Site Equipment:

Typical Site Telescope - 50-70mm Refractor with field flattener.


Site equipment is subject to replacement and upgrade


Transformation Coefficients are available for Johnson and Cousin filters.


How to use the Bright Star Monitor Network

Request telescope time:

To be assigned telescope time, a BSM member simply provides a brief description of the project and the appropriate target information, using the following form, to the Telescope Allocation Committee.

Proposal Form:

The TAC consists of professional and AAVSO member volunteers who have project approval authority for the AAVSOnet, as well as for the BSM Section. The TAC prioritizes BSM Section observing plans that meet one or more of the following purposes:

  • Observe scientifically important and under-observed bright variable stars
  • Support AAVSO Alerts/Campaigns that need more CCD observations
  • Provide for member’s stated educational objectives that can be appropriately supported by the BSM Section resources
  • Support AAVSO Outreach objectives (see’

Input for the proposal (

  1. Member Name and Observer Code
  2. Summary of why the observations of each Target is important scientifically or educationally useful to the member
  3. User’s plan for the data, i.e. AAVSO data base, journal article, education or outreach
  4. Request images be sent to VPHOT (free to members)
  5. Check Variable Star Index (
    • Target(s) name verification to ensure name is listed.
    • Target Sky Coordinates (J2000)
    • Target V magnitude range
    • Appropriate comparison stars with standard photometry. The imaging field is similar to a C chart scale (BSM Field of View is 120 arcmin). Request Comparison stars if none exist here:
  6. Time interval for observations in days
    • To determine cadence use the following relationship: dt > (period / dmag) * e, where dt is the cadence (minimum number of days between observations), dmag, the given magnitude difference, and e, the error in one's observations. Then, for any given star of known (even if only approximately) period and range, and a given observer's average error (BSM: use 0.05)  a reasonable cadence can be calculated.
    • Example:  Period = 214, Vmag range = 12.4 to 9.4, the suggested cadence is three days after truncating.
  7. Filters needed in the session sequence
  8. Number of images to be taken in each filter
  9. Exposure time in seconds, for each filter
    • In general, first determine the V magnitude exposure necessary for your required Signal to Noise Ratio and then follow this ratio: B=2V, R=0.8V, and I=0.7V.  Red and Blue targets will alter this rule-of-thumb.
    • The BSM telescopes operated unguided. At this time we typically limit expsoures to no more than 80 seconds.
  10. Start and finish date for the Project

How to get help:

If you need help with your proposal, the BSM Section administrator is available through email to answer your questions.  Written questions can be also submitted via the AAVSOnet Forum.  Another resource is the AAVSO mentor program ( which is primarily designed to pair new observers with experienced members who can teach them about observing techniques, tools, and methods, but can also be a resource for advice on target selection and interesting projects in support of educational objectives.  Finally, if you are a member new to photometry, there are AAVSO Choice Courses that are available to augment your understanding of CCD observing and photometric analysis. (

Receiving Images

Image Processing

Images can be found here:

Thumbnail images by site:

Note: OC61, SRO and TM061 are large telescopes which are part of the AAVSONet

And here:

Compressed fits images by obscode:

Images can also be sent directly to a member’s AAVSO VPhot account:

BSM Legacy Targets for Adoption

The BSM Section is requesting members consider performing the observer function for several bright star targets already part of the legacy AAVSO Monitoring Survey.  These targets are moving to the latest BSM Section approval protocol.

The AAVSO_Monitoring Survey is a catchall project, containing generally transient objects like PNV_J183657, campaign targets like EE_Cep or b_Per, or just targets where we've been monitoring the field for a long time and continue to do so.

We ask that the adopter write a brief proposal for the Telescope Allocation Committee, perform the photometric analysis and submit the data to the AAVSO International Database.  The images will be available through your VPhot account. A list of current targets is provided in the table below.  

BSM SurveyTarget

Adopter Obscode Date Assigned
BL_Tel WEY 01-15-19
FY_Lib WEY 01-13-19
R_Sct MSD 01-14-19
U_Mon DKS 01-16-19
S_Dor YPFA 01-14-19
EE_Cep DDJ 01-19-19
EU_Del DDJ 01-24-19
GO_Cnc CCHD 01-21-19
R_CrB SPP 01-21-19
RR_Lyr DDJ 01-27-19

Also, see the Input for the Proposal paragraph to find out what is needed for submitting the proposal. Remember that the filters, exposures, etc. for these stars have already been determined and don’t need to be identified. For the science statement, you can indicate that you are responding to this BSM Section request for these legacy AAVSO Monitoring Survey stars. Please indicate your interest in an available target by posting a message in the AAVSOnet Forum. Look for an updated table as other targets are added.  

Volunteers keeping the BSM Network running

Key Member Volunteers

George Silvis developed and maintains the AAVSO Scheduler Automation (ASA) software which is used to dispatch plans to the BSM sites with help from Cliff Kotnik.

A special thanks to Dick Post and the BSM Section Working Group for their contributions to the formation of the BSM Section:

  • Helmar Adler
  • Richard Berry
  • Arne Henden
  • Kenneth Menzies
  • Gordon Myers
  • Mike Nicholas
  • Richard Sabo
  • George Silvis

Our Corporate Sponsors…

  • AAVSO expresses its sincere thanks to the following providers for donation of equipment and software: 
  • DC3 Dreams(ACP)
  • Diffraction Ltd (SBIG Cameras and MaximDL)
  • QSI Corp. (QSI camera)
  • Software Bisque (TheSkyX and Paramount support)
    • Given 5 SkyX site licenses to run with the ParamountMEs
  • Tzec Maun Foundation (Paramount Mounts)
    • Long term loan of 5 Software Bisque Paramount MEs
  • Pierre de Ponthiere (LesveDome)
  • Steve Beckwith (FocusMax)
  • Astrodon (Photometric Filters) 
  • Other vendors who have given discounts include:
    • WatchDirectory (software)
    • MoonLite (focusers)
    • Moonglow (all-sky cameras)



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