Hemisphere:  Northern  ·  Contains:  IC 417  ·  NGC 1931  ·  The star φAur
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IC417/NGC1931 - The Spider and the Fly, 


            Ivaylo Stoynov
IC417/NGC1931 - The Spider and the Fly
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IC417/NGC1931 - The Spider and the Fly

Technical card

Imaging telescopes or lenses: William Optics Megrez 80 FD

Imaging cameras: QHYCCD QHY 22

Mounts: Takahashi EM-200

Guiding telescopes or lenses: ZWO 60/280 GuideScope

Guiding cameras: QHY5L-II Mono

Focal reducers: William Optics FF/FR III 0.8x

Software: PixInsight PixInsinght 1.8 RC7  ·  PHD guiding  ·  photoshop  ·  APT - Astro Photography Tool

Filters: Astrodon HII-3nm

Dates:Dec. 2, 2018March 17, 2019

Frames:Astrodon HII-3nm: 20x900" -40C bin 1x1

Integration: 5.0 hours

Avg. Moon age: 17.72 days

Avg. Moon phase: 52.98%

Basic astrometry details

Astrometry.net job: 2590833

RA center: 5h 28' 55"

DEC center: +34° 23' 49"

Pixel scale: 2.390 arcsec/pixel

Orientation: 231.950 degrees

Field radius: 0.957 degrees

Resolution: 2253x1800

Locations: Nedelkovo, near Sofia, Bulgaria

Data source: Backyard


The Spider and the Fly "pair" are visually close neighbors of the famous Auriga nebulae "Faming Star" (IC405) and "Tadpoles" (IC410). The smaller object in the upper part of the frame is NGC 1913 (Sh2-237) called the Fly. It is considered as smaller version of the Orion nebula – contains a young cluster, it’s Trapezium, has an emission and reflection parts. The brighter object is IC417 (Sh2-234) which should be the spider who waits for prey, laying in the faint web (personally I see more obvious figure in the lower left angle). IC417 also hosts a young cluster (Stock 8) and the two small clouds above the brightest star hide stellar nurseries. The emission part dominates the region, however with the appropriate imaging time is possible show also the reflections from the hot and massive blue stars. A near infra-red study with Spitzer Telescope shows that the bright wave from the Spider towards the Fly hides packs of young stars that maybe form that interesting shape from the clouds located between them and us.

The distances to the objects in the region show curious facts. The two nebulae are ~500 ly away from each other. Respectively ~7 500 and ~7 000 ly from Earth for IC417 and NGC1931. It looks that there is no direct connection in this “pair” as well as with the neighbors - IC405 ~1 500 ly, IC410 ~12 000 ly away from Earth. The whole complex looks very close just visually, but is spread out on more than 10 000 ly in the Orion-Cygnus arm of Milky Way.

Definitely both the Spider and the Fly are interesting objects alone and in pair, so most likely next winter will get back to them for more data.



Ivaylo Stoynov
License: None (All rights reserved)

Sky plot

Sky plot


IC417/NGC1931 - The Spider and the Fly, 


            Ivaylo Stoynov