Horsehead Nebula in SHO (Janne Kontkanen)

Horsehead Nebula in SHO

The Horsehead Nebula in SHO. About 6 hours of exposure in total. 2/3rds of the subs were captured from my patio in San Francisco (Bortle 7), whereas a 3rd was captured during a camping trip to Monterey sand dunes (Bortle 5-6).

A cautionary tale against using a laptop screen as a flat panel:
I am within my first year of astrophotography and this is my first image that uses a ‘proper’ workflow with flats. Previously I had terrible trouble using flats. My flats in the narrowband looked like large concentric rings the size of the whole OTA — something way beyond vignetting. For the longest time, I thought something was wrong with my filters.

However, eventually I realized that the problem was my laptop screen that I was using as a flat panel. It turned out that my laptop has very uneven angular emission, especially on the narrowband frequencies and this caused my problem. This was something that even a white T-shirt between the screen and the scope wasn’t able to fix.

In this image the flats are shot against a white wall instead of the laptop screen. Problem solved

Please note: The following tables are updated every 24 hours.

Distribution of astrophotographers

This table shows the number of distinct astrophotographers who have been assigned and IOTD/TP award compared to the total number of images awarded.
	Distinct awarded users	Total awarded images
Image of the day
Top picks
Top pick nominations

Distribution of subject types

This table shows the distribution of awards per subject type, compared to the popularity of images of that subject type.
	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

Distribution of data sources

This table shows the distribution of awards per data source, compared to the popularity of images acquired from that data source.
	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

The “AstroBin Image of the Day and Top Picks”, or IOTD/TP, is a long-running system to promote beautiful, interesting, peculiar, or otherwise amazing astrophotographs, with a focus on technical excellence. Learn more.

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.

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Astrometry.net job	n/a
PixInsight job	n/a
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