Is It Possible to Do Photometry Without Using a CCD?

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    Ccd Photometry
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Discussion Overview

The discussion revolves around the feasibility of conducting differential photometry without the use of charge-coupled devices (CCDs), specifically focusing on alternative, potentially less expensive electronic detectors for observing stars of magnitude 5 and under. The conversation explores various types of detectors, their sensitivities, and the practicality of using different equipment for photometric measurements.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that while CCDs are inexpensive, they are interested in alternatives like photomultiplier tubes, photodiodes, and photoresistors for differential photometry.
  • Another participant expresses skepticism about the sensitivity of single photodiodes and photoresistors for detecting faint starlight.
  • A participant questions the capability of photoresistors to detect bright stars like Vega and expresses uncertainty about how to calculate their effectiveness using datasheets.
  • One participant argues that using an area detector, such as a DSLR or point-and-shoot camera, is simpler for differential photometry since it allows both the target and comparison star to be captured in the same image.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the effectiveness of alternative detectors for differential photometry, with some expressing doubts about their sensitivity while others propose various options. The discussion remains unresolved regarding the best approach to take.

Contextual Notes

Participants mention limitations regarding the sensitivity of different detectors and the practicality of using them for specific photometric tasks. There are also unresolved calculations related to the effectiveness of certain detectors based on their specifications.

Who May Find This Useful

This discussion may be of interest to amateur astronomers, hobbyists exploring photometry, and individuals looking for cost-effective alternatives to CCDs for starlight detection.

mishima
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CCDs are very cheap, but I was wondering if there was an even cheaper alternative to CCDs if the goal is differential photometry on magnitude 5 and under stars. The data only needs enough precision to prove/demonstrate the concept, and to develop a good sense of the workflow in doing photometry from observational data. Assume I have a 6" Newtonian.

Photomultiplier tubes such as the 1p21 can be found for less than 40$, but require expensive 1000V power supplies.

I am more curious about single photodiodes, or even more crude ways of collecting starlight such as photoresistors. Just wondering if anyone has experimented with some off the beaten path electronic detectors.
 
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mishima said:
I am more curious about single photodiodes, or even more crude ways of collecting starlight such as photoresistors. Just wondering if anyone has experimented with some off the beaten path electronic detectors.

I would suggest that their sensitivities would be way too low for the faintness of starlight
 
A photoresistor could not even detect something like Vega? Just curious, not sure how to calculate something like that using a datasheet.

I was thinking photodiodes at least had been in use a few decades ago.
 
It is much simpler to do differential photometry with an area detector where the target and comparison star can be on the same image. You can use a DSLR or even a point and shoot camea if it can do long exposures.
Regards Andrew