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To stack or not to stack, which is best?

› Forums › Photometry › To stack or not to stack, which is best?

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  • 11 June 2026 at 7:01 pm #640720
    John Coffin
    Participant

    Hi, I am learning how to do photometry in order to flux calibrate my spectra. I am using an 80 mm refractor and an Atik 460 with a field flattener.

    I have been using ASTAP to plate solve and calibrate the individual images. I wanted more control over the process so changed from using ASTAP’s photometry facility and am now using Astroimage J.

    I can’t image for more than 10 seconds before my target is saturated. I collected 20 frames. I found that processing the frames individually or after stacking them made very little difference to the result.

    A typical spectroscopy session lasts for an hour, and I aim to measure the magnitude of the target during this time.

    How many frames should I collect to get an accurate result? I suppose the advantage of processing the frames separately is that I could spot any major fluctuations in the target’s magnitude.

    Any thoughts?

    11 June 2026 at 11:17 pm #640722
    Robin Leadbeater
    Participant

    The nice thing with the individual measurements (both in photometry and spectroscopy) is you can use them to make a true estimate of the stochastic uncertainty (though not any systematic errors)

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