Observing & Reporting

The VSS guide “How to Observe Variable Stars” is the essential short introduction for visual observers using binoculars or telescopes. This begins at the beginning, and covers techniques, charts, and recording and observing, as well as some handy hints about pitfalls.

Once you’re familiar with the VSS guide, please use the AAVSO’s excellent Manual for Visual Observing of Variable Stars. It’s essential reading, and it’s the “official” guide for VSS observers, replacing the old RASNZ-VSS one.

A new and potentially more accurate method of visual magnitude estimation has been developed by VSS member Glen Schrader. See his article “Visual Variable Star Observations” in the February 2010 Newsletter. VSS is carrying out tests on this method in the Dual Maxima Miras Project.


CCD observers should use the AAVSO CCD Observing Manual. The target audience for this manual are beginner- to intermediate-level CCD observers interested in learning how to perform variable star photometry with an astronomical CCD camera.

VSS is preparing its own manual for CCD observing, which will be linked here when completed.

For any target that can change noticeably in a timescale of minutes, it is important to ensure your computer’s clock is set as accurately as possible. This applies to all eclipsing binary and dwarf nova work, amongst others. Dave Herald, an expert in this area, recommends for PC synchronisation these two freeware programs:

  1. Dimension4 – http://www.thinkman.com/dimension4/
  2. BeeperSync – http://hristopavlov.net/BeeperSync/

Reporting and Data Submission

Electronic Data for VSS

Analysis of CCD data can be quite complex, especially when it comes from different observers using different equipment. To save the analyst time and frustration, let alone the need to query you by email, please assist by using the report formats below. In some cases, a VSS Project may have reporting requirements different from the ones here.

Please send data as an email file attachment. Record only one night’s data on one star in one filter in each file.

Please use the ccd_form.xlsx (Excel 2007 format) by preference. In the email, you can advise of any issues or problems.

Alternatively, send a text file (tab separated or CSV), with columns headed (H)JD, Var mag, and optionally Var error, Check mag, Check error, and Airmass. (HJD is preferred to JD – see Calculators for an HJD calculator). In the email body please record:

  • Target star (Var) ID
  • Observer name
  • Observatory location (town, state, country)
  • Evening date UT of observations
  • Telescope aperture (cm)
  • Filter used if any
  • Are your data transformed?
  • Are mags for V differential?
  • Comp star ID
  • Comp catalogue mag
  • Catalogue used for Comp ID and mag (or AAVSO chart designation if that’s what you used)
  • Check Star star ID
  • Chk catalogue mag
  • Catalogue used for Chk ID and mag (or AAVSO chart designation)

The third option is to submit an Official AAVSO Extended Format file, provided:

  • You have only one night’s data for one star in one filter in the file, and
  • You identify the comp star used and the magnitude you set for it. (The comp star ID can be in the file body, but the comp star mag you set will need to be supplied separately. For differential magnitudes, that is 0.0)

In all cases email your report to the leader of the project in which you are working.

Visual Data for VSS

In some cases, a VSS Project may have reporting requirements different from the ones here.

Either the Official AAVSO Visual Format files (preferred), which is supported by the AAVSO PCObs file generator utility.

Or Ranald McIntosh’s RASNZ VSSOBS format.

In all cases email your report to the leader of the project in which you are working.