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I am looking to get started in photometry with a CMOS (or CCD) camera.
I’m afraid most of the discussions on here are like a foreign language to me.
Is there anyone who could guide a beginner. I have a lot of experience in PEP of long period variables
but the techy/jargon around cameras is tricky for me to follow.
I have spoken with a few local (Brighton) imagers who have suggested this route.
I will be buying all equipment from scratch including mount, OTA, camera.
Not even sure what questions to ask.
Perhaps a start could be. What are others observing. What magnitude can useful work be carried out with say C8 or say 100mm APO.
Help please
KevinHi Kevin,
Do you still have any PEP capability, particularly J,H bands ? I am looking for data on RW Cep to complement my spectroscopy as it returns from its deep fade
https://britastro.org/vss/VSSC195.pdf page 7Cheers
RobinKevin:
I was a newbie at CCD photometry until quite recently and I agree the learning curve can be quite steep.
Have you found https://britastro.org/section_information_/variable-stars-section-overview/baavss-mentoring yet?
I may be able to help you but this forum is not the right place to do it in my opinion. If you would like to email me at paul (a) leyland.vispa.com we can see what can be done to get you started. We can’t easily meet in person because I’m in La Palma right now and after returning to Cambridge in a couple of months we will still be a fair distance apart. Phone and/or Skype/Zoom may be helpful as well as email.
Paul
Hello Robin,
I still have my Optec SSP3 photometer but only Johnson IBVR filters. Limiting mag on a 20cm reflector for 0.02 mag accuracy was a measly 7.5mag.
I don’t have a scope yet.
Probably no use to you. Sorry
Regards
KevPerhaps a start could be. What are others observing. What magnitude can useful work be carried out with say C8 or say 100mm APO.
KevinHow long is your piece of string, in other words.
I have done photometry of exoplanet transits, variable stars (eruptives / cataclysmics mostly) and asteroids but exceedingly little on LPVs and eclipsing variables. Extragalactic luminous blue variables have also had a lot of attention but I accept that I am seriously weird in some respects.
Reasonably good estimates for magnitude ranges can be obtained from any one data point scaled by collecting area. Here is my data point, based on a 0.4m aperture. It has four times the collecting area of a C8 and so the limiting magnitude is likely very close to 1.5 magnitudes fainter. A 100mm APO has 1/16 of the collecting area and so will be around 3 magnitudes inferior to a 400mm. Note that essentially all cameras have effectively the same detector sensitivity these days and so the make of the camera is largely irrelevant from a performance point of view.
I can manage 0.1 mag precision at V=20 with a ~3 hour exposure.
I regularly do 0.05-0.03 mag measurements down to V=18 or so.
For exoplanets, ~2mmag precision can be done down to perhaps mag 12-13 unfiltered at a reasonable cadence — 1-2 minutes perhaps.In the words of good old Usenet: HTH, YMMV, HAND.
The above was for photometry. Add another 2 magnitudes or so for usable astrometry. I’ve uploaded images to the gallery where satellites in the outer solar system are visible at mag 22 or thereabouts.
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