Sh2 282 Field Flattening Exercise (Jerry Yesavage)

Celestial hemisphere: Northern · Constellation: Monoceros (Mon) · Contains: LBN 978 · NGC 2262 · Sh2-282

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Sh2 282 Field Flattening Exercise

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Sh2 282 Field Flattening Exercise

I have been trying to get this field as flat as possible with the help of a number of members, especially Jon T, Jerry M and Gary I. This is very tricky and I have learned a lot, so I thought I should put up some notes.

The Stellavue field flattener is custom for the scope which has native FL of about 900. It is F6.9, which makes for a critical focus zone (CFZ) of 6.9*6.9*2.2=104.7 micron or 0.1047 mm.

The image circle of the Stellarvue is 60mm and the diagonal of the ASI 6200 chip is 43 mm. So the 6000x9000 pixel chip is completely covered.

The challenge is that the standard spacers to adjust the field flattener backfocus have a minimal size of 1mm or 1000 microns.

So it is almost guaranteed that you will be either above or below the CFZ. I just pushed it out over the edge and it become defocused in the center rather than the edges.

With the help of Issac at Stellarvue I have in my hands some 0.4 and 0.6 mm spacers.

Anyway, what you see here is good enough for government work, but really this should be done on an optical bench rather than in an observatory...

All that being said I am very happy with the scope and the camera... this is 2h of exposure.

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Status	Advanced success
Started	...
Astrometry.net job	5551289
PixInsight job	3HNNG9OBJVUWMHJ5CDFH5FKLTDMFZ6VU
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	06h37m57s.703
RA (top/left)	06h33m49s.823
RA (top/right)	06h42m13s.141
RA (bottom/right)	06h42m05s.914
RA (bottom/left)	06h33m42s.308

Dec (center)	+01°30′58″.16
Dec (top/left)	+00°47′58″.89
Dec (top/right)	+00°50′46″.25
Dec (bottom/right)	+02°13′54″.34
Dec (bottom/left)	+02°11′08″.52

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Sh2 282 Field Flattening Exercise

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