Photometry with smart telescope

American Association of Variable Star Observers (AAVSO)
Wed, 10/25/2023 - 17:34

 Can i use the Seestar s50 for variable star photometry?

American Association of Variable Star Observers (AAVSO)
SeeStar photometry

Can the SeeStar do photometry? Good question.

Its a color camera like a DSLR so you have to deal with that.

I encourage you to join the Seestar channel in the AAVSO Community Slack workspace. So far we have 3 people contributing what we learn about this very cool instrument.


American Association of Variable Star Observers (AAVSO)
Here are the details:

Sure. Here's my procedure, so far:

  1. Make sure the phone and telescope are attached to their respective chargers;
  2. Turn on the S50 and launch the app on phone or iPad;
  3. Get within a meter or two of the scope and hit Connect;
  4. Click the picture of the scope on the home screen of the app;
  5. Turn on "Anti-Dew" and under "Focus", turn on "Focus Panel";
  6. Under "Advanced Feature[s]", deselect "Auto Shut Down" and select "Save each frame in enhancing";
  7. The following presumably you need to do only once in a while:
    1. Under "Advanced Feature[s]", perform "Compass calibration";
    2. Unscrew the telescope from the tripod and, as best you can, level the tripod using the air bubble device. This is not easy. I have been using wooden shims with mixed success;
    3. Carefully screw the scope back onto the leveled tripod (also not easy) and perform "Level sensor calibration";
  8. Unless you have just calibrated the level sensor, perform "Adjust level" to the point the deviation is under 1.0 (also not easy);
  9. Return to app main screen and select "Stargazing";
  10. Search the database for an well-known object near RZ Cas, e.g. Ruchbah;
  11. When the blue rectangle (actual FOV) and the red rectangle overlap substantially, interrupt the "GoTo/Shooting" process;
  12. Pause briefly, then drag the red crosshair to RS Cas (which, even though it's not in the database, is labeled on the map);
  13. Press "GoTo" and wait until the system switches from the star map screen to the sensor image screen;
  14. Manually guide the scope so RZ Cas falls within the pale white disk. Make sure the slewing is set to Slow;
  15. I am not sure if after manual guiding, it will help tracking to go back to the star map screen (click the Big Dipper button) and hit "Sync". If you do that, the system takes you back to the sensor image screen without your intervention;
  16. Between eclipses, the magnitude of RZ Cas is 6.2, and the system is programmed to capture one image every 10 seconds. I don't know if the sensor is actually collecting photons for 10 seconds, but the exposure time is long enough to saturate the pixels hit by the light from RZ Cas, even on a cloudy night. As far as I know, the exposure time interval cannot be changed, at least not in this release of the S50 app/firmware (v1.83), so the only way to avoid saturation is to defocus. The default focus position on my S50 is 1663, and I used the focus panel on the left side of the sensor screen to change that value to 1803, creating illuminated discs large enough to avoid pixel saturation. Going much past 1800 makes it hard for to perform a plate solve, a necessary step because the S50 fit files don't include the RA and Dec of objects in the field. Presumably, the optimum focussing position will be target-and weather-dependent, but so far 1803 seems to work well;
  17. Click the big red button, initiating the image enhancement process;
  18. Watch the process run through a few cycles and click the red square to stop;
  19. Pull out the charging cable and use the same UBC port to connect to a laptop running AstroImageJ;
  20. Import into AstroImageJ the handful of fit files you captured and check for two things:
    1. signs pixel saturation (indicating you need to defocus more); and
    2. failure of to plate solve (indicating you need to defocus less).
  21. Eject the Seestar resource and replace the data-transfer cable with the charging cable;
  22. Go back as far as necessary in this procedure to get to the step where the sensor screen image is centered on RZ Cas;
  23. Adjust the focus position, if indicated, and "Restart" (rather that "Continue") the enhancement process;
  24. Watch the system go through a few 10-second cycles and go to bed; 
  25. In the morning, connect the data transfer cable and import into AstroImageJ only a small fraction of the hundreds of fit files created overnight, e.g., every 10th file;
  26. Debayer (GRGB) the imported images and perform a WCS/ plate solve (takes a while) and perform a pretty-much standard multi-aperture analysis. See: Dennis Conti's excellent tutorials.

Looking forward to hearing about other people's improvements to this methodology.

Take care,


Variable Stars South (VSS)
Hi Richard,

Thanks. Very…

Hi Richard,

Thanks. Very comprehensive. I didn't mean for you to go to the trouble of that detail.

I thought the exposure was probably limited to 10 secs. My other specific question was how often does the Seestar take images?

Also, what gain do you see in your FITS headers?


American Association of Variable Star Observers (AAVSO)
Seestar S50 FITS file after debayer and plate solve

No problem, I like to write out my procedures because these days the half-life for my remembering them is about a week.

Ah, yes. Look in the FITS file! Exposure time is 10 s. Gain is 80. Once the enhancement process gets started, an image is captured maybe every 12-15 seconds. One ends up with way images than I have the patience to plate solve.




American Association of Variable Star Observers (AAVSO)
Great stuff Richard.I also…

Great stuff Richard.

I also have a SeeStar S50 coming in a couple of days and am also looking to try and do some Photometry with it.

I already have all of the proper filters and need to just to 3D print up a holder for them.

I did join the  Seestar channel in the AAVSO Community Slack workspace that was mentioned above also.


-Tom Mihelich

Variable Stars South (VSS)
See the DSLR Observing Manual


The Seestar S50 has a colour (RGB) sensor. Photometry with this sensor should therefore be performed using the same principles applied to photometry with a DSLR camera.

See The AAVSO DSLR Observing Manual.

It is not appropriate to use scientific photometric filters in the imaging train.


American Association of Variable Star Observers (AAVSO)
Tripod Leveling for light loads like the SeeStar 50

I use a: CAVIX Camera Leveler Tripod Leveling Base for fine tuning the level once the tripod is approximately level.

Available on several venues.