IC 410 and IC 405: Tadpoles and the Flaming Star...

IC 410 and IC 405...

Object(s): IC 410 and IC 405
Type: Emission nebulae
Constellation: Auriga
Distance: 12,000 light years (IC 410) and 1500 light years (IC 405)
Equipment: Atik 460/EFW 2, Samyang 135mm lens@ F2, Vixen GPDX mount, guiding with Lodestar X2/PHD
Date: January 21st. 2023
Subframes: 18 x 300s each for Ha (1x1 binned) and OIII (2x2 binned), 12 x 200s (2x2 binned) for RGB: flats, bias as dark frames.

Location of the field of view in the night sky...

This particular area of the Orion Milky Way, beneath the constellation of Auriga, offers a rich zone of targets for any astrophotographer.  It is an area that I have visited several times before, but the 5 degree field of the Samyang f2 lens offers a chance to place many targets in the same field of view, to show their proximity to each other.

At the top left of the field of view lie the two open clusters, M38 and NGC 1907. I imaged these back in 2010: these clusters lie at around 4500 light years away, in between IC 410 and IC 405. 

Below these clusters lie "The Spider and the Fly", IC 417 and NGC 1931. I imaged these nearly three years ago . 

Discovered by Max Wolf on September 25th 1892, IC 417 ("the Spider") is a star cluster with an associated emission nebula, and lies about 7500 light years away. A wider area of hydrogen alpha emission extends from it and is classified as Sharpless 2-234. The smaller but brighter NGC 1931 was discovered by William Herschel on February 4th 1793, and is also an emission nebula with an associated cluster, as well as an element of reflection nebula. It, too, has a Sharpless designation (Sh2-237) and lies at a similar distance to IC 417.

Designations of the objects in the image field of view...

IC 410 is very much a background object, lying over 12,000 light years away. It is often called the "Tadpoles" nebula, after the two blobs of star-forming dust and gas within it, designated as Simeis 129 and 130 respectively, and which just about show up on the main wide field image above. I pictured these back in January 2019. The nebula IC 410 was discovered by Max Wolf on September 25th. 1892, and strictly speaking the IC 410 designation refers to the brightest area of nebulosity surrounding open cluster NGC 1983, an earlier John Herschel discovery from January 22nd 1827. These days, IC 410 is taken to be the entire nebula, which also has the Sharpless designation Sh2-236.

IC 405 (also designated Caldwell 31 by Sir Patrick Moore in his own catalogue of deep sky objects) is the "Flaming Star" nebula, which I pictured back in December 2019.  It was discovered on March 21st. 1892 by John Schaeberle. IC 405 also has a wider area of H-alpha nebulosity associated with it, designated as Sh2-229, although they all tend to be regarded as "IC 405" these days. At a mere 1,500 light year distant, it is a foreground object compared to the others in this field of view.

The whole area is designated as Sharpless 2-230.  I did take a wide field image of Sh2-230 back in January 2009, but since then both my equipment, software and processing techniques have improved (though the mount is still the same!)

In terms of processing, the biggest problem is that the nebulae are overwhelmed by a blizzard of the Milky Way stars. The magic of the "Starnet" software was used to "de-star" the various narrowband and colour image stacks, allowing me to replace just the brighter stars and clusters back into the image at a more visually aesthetic level.

The Spider and the Fly...

NGC 1931 and IC 417

Objects: NGC 1931 (star cluster with emission/reflection nebula Sharpless 2-237, IC 417 (Sh2-234, Spider nebula, with star cluster Stock 8)
Type: Emission Nebulae 
Constellation: Auriga
Distance: 7500 light years

Dates: 12th. March 2020
Equipment: ATIK 460EX with EFW2, Skywatcher f5.5 Esprit 100 ED refractor, Avalon Linear mount, guiding with Lodestar X2/PHD

Subframes: 3 x Red (300s, 2x2 binned), 3 x Green (300s, 2x2 binned), 6 x Blue (450s, 2x2 binned), 9 x 600s H-alpha, flats for each channel, no darks (hot pixel removal in Astroart).

Stellarium map showing field of IC 417

Between Theta Aurigae and Iota Aurigae (the two southernmost stars of the “kite” of the constellation of Auriga) lies a string of emission nebulae. The above image shows another two faint areas of nebulosity lying between the brighter and better known nebulae IC 410 and IC 405 and the "Pumpkin Patch".

Two large OB associations have traditionally been identified in the constellation of Auriga, aligned one behind the other. The first is indicated with the abbreviation Auriga OB1.  Twelve stars of the spectral classes O and B were initially designated as effective members of the association, to which are added three red supergiants at the end of their life cycle. The suggested distance was about 1750 parsecs and was therefore placed on the galactic Arm of Perseus.  The second association is indicated as Auriga OB2 and eight class O and B stars were associated to it, mostly on the main sequence; its distance was indicated at least 6300 parsecs, i.e. in a remote area of the outer disk of the Milky Way, on the Cygnus Arm.


The estimated distance of IC 417 suggests it to be close to the Auriga OB1 association.

The image itself is fairy noisy, as clouds cut short the imaging session and I was only able to grab nine Ha frames to use as luminance: not that I would have been able to get to many more anyway, as the object was sinking into the western horizon.