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Contains:  B286, B287, M 7, M7, NGC 6453, NGC 6475, NGC6453, PK355-04.1, PK355-04.2, PK356-04.1, Ptolemy cluster, Ptolemy's Cluster
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M7 - Ptolemy's Cluster

Technical card

Dates:June 25, 2002June 25, 2020

Astronomik B 31 mm Type IIc: 8x30" (gain: 139.00) -15C
Astronomik G 31 mm Type IIc: 9x30" (gain: 139.00) -15C
Astronomik L 31mm Type IIc: 25x30" (gain: 139.00) -15C
Astronomik R 31 mm Type IIc: 8x30" (gain: 139.00) -15C

Integration: 0.4 hours

Darks: ~30

Flats: ~30

Avg. Moon age: 9.86 days

Avg. Moon phase: 59.72%

Bortle Dark-Sky Scale: 4.00 job: 3640678

RA center: 17h 53' 56"

DEC center: -34° 54' 1"

Pixel scale: 1.294 arcsec/pixel

Orientation: -126.845 degrees

Field radius: 0.991 degrees

Resolution: 4350x3388

Data source: Traveller


This is probably my new favorite cluster that I've shot. I decided to knock out 4 of the low declination Messier clusters in one night. Being on a beach facing south really helped out with the light pollution, and I only needed so sink a half hour into each of the clusters, compared to the hour I'd normally do from my bortle 7 apartment roof. Unfortunately my guide camera refused to talk to my laptop, so my telescope was at the mercy of the wind. I'm really surprised with how well this turned out, even with my blue stack being affected by haze. Captured on June 25th, 2020 from a Bortle 4 zone.



* TPO 6" F/4 Imaging Newtonian

* Orion Sirius EQ-G

* ZWO ASI1600MM-Pro

* Skywatcher Quattro Coma Corrector

* ZWO EFW 8x1.25"/31mm

* Astronomik LRGB+CLS Filters- 31mm

* Astrodon 31mm Ha 5nm, Oiii 3nm, Sii 5nm

* ~~Agena 50mm Deluxe Straight-Through Guide Scope~~

* ~~ZWO ASI-120MC for guiding~~

* Moonlite Autofocuser

**Acquisition:** 24.5 minutes (Camera at Unity Gain, -15°C)

* Lum- 25x30"

* Red- 8x30""

* Green- 9x30"

* Blue- 7x30"

* Darks- 30

* Flats- 30 per filter

**Capture Software:**

* Captured using [N.I.N.A.]( ~~and PHD2 for guiding and dithering.~~

**[PixInsight Processing](**

* BatchPreProcessing

* StarAlignment

* [Blink](

* ImageIntegration

* DynamicCrop

* AutomaticBackgroundExtraction 2X

* **Luminance:**

* TGV/MMT Noise Reduction

* ArcsinhStretch

* HistogramTransformation

* **RGB:**

* LinearFit to green

* ChannelCombination

* AutomaticBackgroundExtraction

* PhotometricColorCalibration


* HSVRepair

* ArcsinhStretch

* HistogramTransformation

* LRGBCombination with Lum

* CurveTransformations

* HistogramTransformation

* UnsharpMask

* MorphologicalTransformation to reduce star sizes

* Invert>SCNR>Invert

* More Curves

* Annotation



License: None (All rights reserved)

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M7 - Ptolemy's Cluster,