The AAVSO has kinly sent me an acknowledgement for “your invaluable contribution of over 2,500 variable star observations by Photoelectric Photometry to the AAVSO International Database through September 2024”.
I am very grateful for this recognition, based on my photoelectric photometer measurements using the technique called PEP (Photoelectric Photometry), and I take this opportunity to talk about it here.
The PEP technique seems to go back to the past of photometric measurements in the era of advanced CCD and now CMOS cameras. Instead of using a two-dimensional sensor it uses a single pixel, which can be a photodiode or a photomultiplier. In my case I use a photomultiplier in a setup I designed myself (https://www.observatorio-majadahonda.com/fotometro-estelar).
Few observers use this technique and one may wonder why, when CMOS sensors offer very advanced technical qualities and extraordinary results in photometry. The fundamental reason is that with CMOS sensors it is very difficult to do photometry of bright stars, mainly for these reasons:
The sensor saturates quickly and if we lower the exposure time to avoid saturation we will have serious scintillation problems.
It is difficult to do differential photometry with a bidimiensional sensor, because even though the sensors are getting bigger, if the star is very bright, we will not find another in the field of similar brightness to do good photometry.
In short, precise photometry of bright stars is very difficult with CCD or CMOS sensors, but with the PEP technique, accuracies (or rather uncertainties) of the order of a thousandth of a magnitude can be achieved.
The PEP technique requires a photometer and procedures that are well described on the AAVSO web site(https://www.aavso.org/aavso-photoelectric-photometry-pep-section). The photometer can be purchased second hand (if you pay attention, they only come up for sale occasionally) or you can build your own.
If you want to understand how the one I built works, here is an explanatory video:
Commentaires