Spaghetti Nebula, Sh2-240, Simeis 147 (Jared Willson)

Spaghetti Nebula, Sh2-240, Simeis 147

Link: https://skylightobservatory.com/spaghetti

The Spaghetti Nebula is a supernova remnant lying on the border between Taurus and Auriga. Despite covering a large area of sky (roughly three degrees across), it wasn't discovered until 1952 because the surface brightness is extremely low. It was found in 1952 on narrow band photographic plates taken at the Crimean Observatory. This supernova remnant has an estimated age of 40,000 years. At the estimated distance of 3,000 lightyears, that would correspond to a physical size of roughly 160 lightyears. That means the remnants of the explosion have been traveling outwards from the source explosion at more roughly 2.5% of the speed of light or 7,500 km/s. At that speed, the trip from New York to London would take just three quarters of a second!

The supernova that created Simeis 147 left behind a pulsar, a spinning neutron star that emits radio waves that appear to pulse as the star rotates, much like a lighthouse light. The pulsar PSR J0538+2817 which was found in 1996 is thought to be the remains of the star that exploded to form this nebula. You can see the location of PSR J0538+2817 marked in green in a second uploaded version of the image. It does not have an obvious visible light counterpart, so only the marked location can be seen. The pulsar has a relatively slow period (for a pulsar) of 143 ms.

This is an HOO image with RGB stars. That means the nebulosity was captured in H-alpha and doubly ionized oxygen. The hydrogen emissions were mapped to red, and the oxygen emissions were mapped to both green and blue. This is fairly close to a true color representation of the two gasses as hydrogen alpha is, in fact, a deep ruby red color, and OIII is a teal color, roughly halfway between blue and green. Straight HOO images generally look somewhat artificial since it is impossible to get accurate star colors with just two wavelengths of light. As a result, a relatively small dataset of red, green and blue was used for just the stars themselves.

Astro-Physics APCC was used for mount control and for building a large tracking model of the sky. The mount was also guided using a separate guide scope and PHD2 software using half second exposures. Because of the large size of the subject, NINA was used to setup a twelve panel mosaic in order to frame the entire target. There are four rows and three columns of images combined into the final result. Mosaics across such a large swath of sky are challenging as a result of light pollution gradients. This process was helped tremendously by the recent release of PixInsight MARS data which allows very accurate gradient correction based on reference frames. NINA was used for all image capture and hardware control. PixInsight was used for pre and post processing of the image. The PixInsight software tools utilized included (in approximate order):
- Weighted Batch Pre-Processing
- Multiscale Gradient Correction
- Photometric Mosaic
- BlurXTerminator (correct only)
- StarXTerminator
- Channel Combination
- Narrowband Normalization
- Generalized Hyperbolic Stretch
- HDRMT
- NoiseXTerminator

Final
Original
B
C
D

B

Title: Pulsar Location

Description: The location of PSR J0538+2817, the pulsar remnant from the original supernova explosion, is marked in green. There is no optical component--just radio

Uploaded: ...

C

Title: Simeis 147, H-Alpha

Description: Starless Hydrogen Alpha data

Uploaded: ...

D

Title: Simeis 147, OIII Data

Description: Starless Simeis 147 in OIII

Uploaded: ...

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Status	Advanced success
Started	...
PixInsight job	E6FOPTF9UDU6NQ3NS7LP57HGRZLC4SSK
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	05h41m12s.62
RA (top/left)	05h50m56s.43
RA (top/right)	05h50m57s.41
RA (bottom/right)	05h31m01s.36
RA (bottom/left)	05h31m53s.26

Dec (center)	+28°05′10″.2
Dec (top/left)	+25°39′09″.1
Dec (top/right)	+30°33′33″.5
Dec (bottom/right)	+30°28′32″.6
Dec (bottom/left)	+25°34′17″.9

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