Celestial hemisphere:  Northern  ·  Constellation: Hercules (Her)  ·  Contains:  M 92  ·  NGC 6341
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M@H 92: Damned precession!  a city view of M92, 



    
        

            Edoardo Luca Radice (Astroedo)
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M@H 92: Damned precession! a city view of M92

Getting plate-solving status, please wait...
M@H 92: Damned precession!  a city view of M92, 



    
        

            Edoardo Luca Radice (Astroedo)
Powered byPixInsight

M@H 92: Damned precession! a city view of M92

Acquisition details

Dates:
April 15, 2020 ·  April 16, 2020
Frames:
Baader Green (G-CCD) 2": 7×300(35′) bin 1×1
Baader Planetarium B 2": 7×300(35′) bin 1×1
Baader Planetarium Baader 1,25" L: 14×300(1h 10′) bin 1×1
Baader Red (R-CCD) 2": 6×300(30′) -25°C bin 1×1
Integration:
2h 50′
Darks:
30
Flats:
20
Flat darks:
20
Bias:
50
Avg. Moon age:
23.12 days
Avg. Moon phase:
39.75%
Bortle Dark-Sky Scale:
7.00
Mean SQM:
18.70

RA center: 17h17m43s.699

DEC center: +43°0700.29

Pixel scale: 0.514 arcsec/pixel

Orientation: 89.660 degrees

Field radius: 0.405 degrees

More info:Open 

Resolution: 4422x3552

File size: 19.8 MB

Locations: Castenedolo, Castenedolo, Italy

Data source: Backyard

Description

Sometimes even simple errors may be instructive!

This picture of M92 is off center: it seems a simple pointing error, but nowadays pounts are very precise, and SGPRO checks the correct pointing before beginning the sequence so what's wrong?

So, the difference in position is caused by Earth lunisolar equinox precession.

I set in SGPRO the position of M92, got from SkySafary at 2020 equinox (already corrected for precession) but the mount expected Coordiantes at 2000 equinox so corrected (again) for precession.

Result: In this image the off center of M92 is exactly the amount of the precession in 20 years.

Comments

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M@H 92: Damned precession!  a city view of M92, 



    
        

            Edoardo Luca Radice (Astroedo)

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