Celestial hemisphere:  Southern  ·  Constellation: Ophiuchus (Oph)  ·  Contains:  M 19  ·  NGC 6273
M19 (RGB) - 15 May 2020, Geof Lewis
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M19 (RGB) - 15 May 2020

M19 (RGB) - 15 May 2020, Geof Lewis
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M19 (RGB) - 15 May 2020

Equipment

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Acquisition details

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Description

This is the last and most challenging of the three globular clusters that I imaged on 15 May 2020. This cluster just clears 10 deg altitude at my location, but it's maximum altitude at transit is blocked by a neighbour's house, as seen from my observatory, so I had to capture the data for these as it was rising at around 8-9 deg altitude. Even then I discovered that the green data was being imaged through tree tops, so most of that already thin data had to be discarded. To get a reasonable (and that is open to question) RGB image, I mixed the 4x2m usable G subs with a synthetic green made with the RB subs.

Overall the guiding this low down was very poor with Dec having the worst of times, resulting in egg shaped stars, which I tried to improve, but couldn't really fix in post processing.

This is a target that I've never imaged previously, so wanted it for my personal Messier collection which now stands at 101/110. Unfortunately there are 8 Messier targets that I still need that are even lower than M19, so I'm not sure when, or even if ever, I'll be able to complete the list.

Comments

Revisions

  • M19 (RGB) - 15 May 2020, Geof Lewis
    Original
  • M19 (RGB) - 15 May 2020, Geof Lewis
    B
  • M19 (RGB) - 15 May 2020, Geof Lewis
    C
  • M19 (RGB) - 15 May 2020, Geof Lewis
    D
  • M19 (RGB) - 15 May 2020, Geof Lewis
    E
  • M19 (RGB) - 15 May 2020, Geof Lewis
    F
  • Final
    M19 (RGB) - 15 May 2020, Geof Lewis
    G

B

Description: Star elongation fix using PS provided by Niall MacNeill (thanks Niall)

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C

Description: Blend of original and vers B (50% opacity)

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D

Description: My own attempt at star elongation fix using PS (CS2).
NB advanced plate solve failed even with prompts and uploaded raw image

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E

Description: Alternative elongated stars fix using masked brush

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F

Description: Layered versions E and D for better core stars in D

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G

Title: Reprocessed using PixInsight.

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Sky plot

Sky plot

Histogram

M19 (RGB) - 15 May 2020, Geof Lewis