Celestial hemisphere:  Northern  ·  Constellation: Cepheus (Cep)  ·  Contains:  NGC 7023
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Iris and the Ghost (NGC 7023 to vdB 141 area), snakagawa
Iris and the Ghost (NGC 7023 to vdB 141 area)
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Iris and the Ghost (NGC 7023 to vdB 141 area)

Getting plate-solving status, please wait...
Iris and the Ghost (NGC 7023 to vdB 141 area), snakagawa
Iris and the Ghost (NGC 7023 to vdB 141 area)
Powered byPixInsight

Iris and the Ghost (NGC 7023 to vdB 141 area)

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Description

This is my last image from C8 Fastar+Hyperstar combination, before the corrector plate got smashed during day-time collimation.... (sad)

C8 Faster (black)+ Hyperstar 3; SXVR-M25C at -15 deg C

An aperture mask was used to improve FWHM (F/2.1 increasing to F/2.66 [F/3 effective])

10min x 29

2min x 15

Slightly cropped near the bottom and the left for collimation errors.

A Hyperstar used with a large CCD chip (such as in M25c) results in strong light fall off which is difficult to correct with flats. The aperture mask improved this, making about 2/3 of the center field (linear) more or less flat. However, the fall off near the edge was still quite severe, the intensity dropping to ~50% of the field center. The original flats were adjusted slightly on ImagesPlus to reducer errors.

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Iris and the Ghost (NGC 7023 to vdB 141 area), snakagawa