NGC 7635 (Bubble Nebula) with M52, HαRGB, 27-29 Aug 2017 (David Dearden)

NGC 7635 (Bubble Nebula) with M52, HαRGB, 27-29 Aug 2017

Yet another favorite target I wanted to look at again with the ASI1600MM-Cool. I love the larger field of view I get with this camera. Lost some potential data on the first night because the camera download stalled and stopped the session. I don’t think the problem was actually the camera; rather it is a cheap USB hub. I moved the cable to a better hub on the second night and had no further problems, so I’ll keep my fingers crossed. I’m still struggling a bit to get good flats to prevent background color casts, but GradientXTerminator does a pretty good job of “fixing” things. Once again, there’s way more excited state H in this area than meets the eye without the Hα filter. This is HαRGB using pure Hα for luminance and an HαR blend for the R channel.

Date: 27-29 Aug 2017

Subject: NGC 7635 (Bubble Nebula) and M52 open cluster

Scope: AT8IN + High Point Scientific coma corrector

Filters: ZWO 31 mm diameter unmounted Hα (7 nm), R, G, B

Mount: EQ-6 (EQMOD 2.000j)+PEC

Guiding: Orion Thin Off-axis Guider + DSI +PHD 2.6.3.7 (Win 10 ASCOM) using predictive PEC algorithm

Camera: ASI1600MM-Cool, -20 °C, Gain 139 Offset 21

Acquisition: Sequence Generator Pro 2.6.0.24

Exposure: 30x180 R, 30x180 G, 30x180 B, 40x300 Hα

Stacking: Neb 4.1.6, flats & darks, trans+rot align, Nebulosity 1.5σ stack and align.

Processing: StarTools 1.4.328: Stretched and deconvoluted Hα in StarTools, but was not particularly aggressive because I saw no improvement. Combined RGB in Neb 4 and stretched, color balanced, in StarTools. Layered Hα on R (80:20) to produce HαR, which I used for R. Used Hα for luminance. Applied GradientXTerminator to remove some residual green color cast from imperfect flat correction. Tweaked the colors using per-channel saturation and Levels. AstroFrame.

Original
Final
B

B

Description: Some slightly different color choices. I think I like this one slightly better.

Uploaded: ...

Narrowband imaging
ZWO ASI1600MM/QHY163M

	Distinct awarded users	Total awarded images
Image of the day
Top picks
Top pick nominations

	Image of the day	Top pick	Top pick nominations	Total submitted
Deep sky
Solar system
Extremely wide field
Star trails
Northern lights
Noctilucent clouds
Landscape

	Image of the day	Top pick	Top pick nominations	Total submitted
Backyard
Traveller
Own remote observatory
Amateur hosting facility
Public amaeteur data
Professional, scientific grade data
Mix of multiple sources
Other
Unknown

Submitted The date and time when you submitted this image for IOTD/TP consideration.	...
Views by Submitters (available since September 19th, 2023) Every image is assigned to 50% of available Submitters. In the event that at least 80% of them don't view the image before its time in the IOTD/TP process expires, it's assigned to the other 50% of Submitters and the process begins anew.
Promotions by Submitters When 3 distinct Submitters promote the image, it moves on to the next stage of the process: evaluation for Top Pick status. This requirement, in addition to anonymization of images and distribution to only a subset of them, prevents biases and ensures that the best images are selected.
Promotions by Reviewers When 3 distinct Reviewers promote the image, it moves on to the next stage of the process: evaluation for IOTD status.
Early dismissal Staff members have a lot of images to inspect on a daily basis, and they can dismiss images if they believe they don't meet the requirements for IOTD/TP selection. If an image is dismissed 5 times, it's removed from the process. This streamlines the process and ensures that any bias present in promotions could be overruled by other staff members.

Status	Advanced success
Started	...
Astrometry.net job	1709044
PixInsight job	OA903S7DFJSV6BIHYR06TVR9O0E1YULQ
PixInsight queue size	n/a
PixInsight stage	n/a

RA (center)	23h22m05s.339
RA (top/left)	23h17m34s.108
RA (top/right)	23h26m15s.104
RA (bottom/right)	23h26m42s.834
RA (bottom/left)	23h17m48s.777

Dec (center)	+61°20′06″.80
Dec (top/left)	+60°57′58″.71
Dec (top/right)	+60°54′37″.29
Dec (bottom/right)	+61°41′40″.85
Dec (bottom/left)	+61°45′06″.92

Image Index:

Contribution Index (beta):