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American Association of Variable Star Observers (AAVSO)
Mon, 07/10/2023 - 08:38
Dear observers, explain please where to find airmass and how to add airmass to fits file, or, better, how to add airmass automatically with VPhot directly.
VPhot itself will not compute the airmass; it assumes it will be provided in the FITS header.
But TransformApplier will compute the airmass if the observatory location is included in the VPhot Telescope Profile and the FITS header has not provided the number. TA will include that value in the transformed webobs report.
When submitting an image to VPhot that has been stacked (to achieve higher SNR), how should the AIRMASS be calculated from the stacked n images? Each of the n images contain the airmass at the time of the exposure.
Also, each set of n images are exposed within a 20 min timeframe.
Is it the average of all the n stacked images' AIRMASS?
Eg.
image filter AIRMASS
1 B 1.3
2 B 1.5
3 B 1.5
stacked image AIRMASS being submitted to VPhot:
AIRMASS = 1.43 ?
TransformApplier calculates the AIRMASS. Does "Two Color Transform" do that also?
VPhot itself will not compute the airmass; it assumes it will be provided in the FITS header.
But TransformApplier will compute the airmass if the observatory location is included in the VPhot Telescope Profile and the FITS header has not provided the number. TA will include that value in the transformed webobs report.
George
Good news, George, thank you! Well, the transformation will be on the next stage of my learning.
Hi,
When submitting an image to VPhot that has been stacked (to achieve higher SNR), how should the AIRMASS be calculated from the stacked n images? Each of the n images contain the airmass at the time of the exposure.
Also, each set of n images are exposed within a 20 min timeframe.
Is it the average of all the n stacked images' AIRMASS?
Eg.
image filter AIRMASS
1 B 1.3
2 B 1.5
3 B 1.5
stacked image AIRMASS being submitted to VPhot:
AIRMASS = 1.43 ?
TransformApplier calculates the AIRMASS. Does "Two Color Transform" do that also?
Thanks
When TA does aggregates images, the equivalent of stacking, it computes and average airmass for the stack.
George