AAVSO report tabular data and graphics do not match
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Hi Han,
I have a AAVSO report where tabular data and graphics do not match:
the variable markers are not placed properly at their data values
some check star magnitudes are about 0.6 mag dimmer than the other values (probably faulty in some way) but are not shown in the diagram
all comp star magnitudes in the table are identical (11.611 mag) but the markers in the graph definitely show different brightness
I have attached graph and table. Could you please have a look?
Thanks and cs
Axel
Hi Thomas,
If this is a bug it has to be fixed. I have marked the first values. Where do they not match? See screen shot.
Cheers, Han
Hi Han,
the variable markers are not placed properly at their data values
Check for example the last three values: in the table the third-last and the last value are identical (11.453) but in the graph they are not. It would be easier to see if the tick marks would be set at even values rather than starting with an arbitrary origin value.
some check star magnitudes are about 0.6 mag dimmer than the other values (probably faulty in some way) but are not shown in the diagram
the list contains a number of KMAG values of about 11mag that do not appear in the diagram at all. The fourth KMAG value is e.g. 11.613 mag but in the diagram there is a gap in the KMAG markers at the locations of the fourth measurement. The same gaps can be found whereever KMAG table values are 11.613 mag.
all comp star magnitudes in the table are identical (11.611 mag) but the markers in the graph definitely show different brightness
All CMAG values in the table are identical. In the diagram they clearly vary around 11.6 mag and are obviously not identical.
cs Axel
The graph values are based on the Gaia ensemble only. Probably it is better to modify that once a comp star is selected. Then the comp star will write a straight line and the other adapt accordingly. I will look into that.
Cheers, Han
I made a modification. Looks good. Try this version and tell me if this works for you:
http://www.hnsky.org/astap_setup.exe
Cheers, Han
Yes, looks good. I see that in the txt file some KMAG entries have been marked as 'invalid' - is that new? Do the check star error bars show the sigma value noted at the end of the check star entry in the drop down list?
cs Axel
Invalid could be either saturated or below detection level. You will could trace it back in the columns with the measured values tab photometry. You could increase the satuaration level with the check mark in tab photometry.
The error bars are based on the standard deviation of the check star(s) based on Gaia reference. The bar shows 2.5 * standard deviation range. According statistic the real value should be in 99% cases within this range assuming it has a normal distribution.
Note the small difference between Gaia and using check stars.
Once you select a single check star the check line is straight. With more then one check star a variation will occur because they disagree.
The check stars are combined using a weight factor based on the flux.
It has all has become a little complicated so if you can check each time and report any abnormal or suspicious thing, please do. All my personal observations are deep sky only and no photometry so my testing time is limited.
Cheers, Han
Han,
thanks so much for your quick response. In my vacation I am currently monitoring up to 3 or 4 variables each night so there is plenty of material to check if everything works. I am happy if I can help to improve ASTAP.
I tried to adapt the aperture and annulus values to the cramped conditions in a dense star field but failed. Is there a chance to have an interactive mode where one can change the values in the boxes and see immediately in an image how large the circles will come out?
cs Axel
Currently the only way to see the aperture and annulus is to select in tab photometry "manual star selection", click on a few stars and press play. The the aperture an annulus are shown. Press escape to stop.
If the purple circle appears in manual selection mode there is a lock on the star. If there is a lock then an aperture of 1.8 or similar should work. Can you send me an original image demonstrating the problem?
Cheer, Han
The purple circles are objects which shape I can't change except changing them into a square, star or triangle. Drawing a free form object directly on the displayed image is less attractive because removing them is more difficult.