HH 415

GYULBUDAGHIAN'S NEBULA

Gyulbudaghian's Nebula is a reflection nebula around PV Cephi which is in quite a large dust cloud. Like other such nebulae in the dust around newly forming stars, it is a variable nebula. Hubble's Variable Nebula is the most famous but there are others such as NGC 1555, aka Hind's Variable Nebula, lit by T Tauri. Gyulbudaghian's Nebula is yet another example. Checking the POSS 2 plates there is a huge change between the time the red and blue images were taken.

I first imaged this one on September 24, 2011 under very good conditions. After seeing some low resolution images taken in the fall of 2013 that appeared to show a change I put it back on the to-do list. Seeing and transparency never cooperated. About the time it was getting too far west I had a go at it anyway on December 24, 2013. Poorer seeing and transparency conditions make a comparison impossible other than to say it has obviously changed greatly over the 27 months.

I then put it on the to-do list for a retake in 2014. Weather sort of cooperated on September 15 for the luminance data. I lost all color data to clouds. I tried again on the 16th. Seeing was much worse but transparency better. At least at the start. The red data was good just fuzzy from seeing. Green was fair and blue had very poor transparency. This may be why the red portions of the nebula it lies in is much redder this year. I tried again until the moon made that impossible. I finally gave up and went with this data since it shows the nebula has obviously changed and later attempts would likely be of a yet different nebula with different colors so I couldn't use the color data anyway.

Recently I saw a low resolution image of the area that indicated the nebula had changed so I put it on the high level to-do list. I wasn't surprised by this as when I tried for more color data in 2014 showed me it had changed even in the two weeks between tries for more color data. Unfortunately, my horrid weather continues and I wasn't able to get even as much data as I had for the prior year. Luminance was 5 instead of 8 subs through far poorer transparency. I had to push things a lot to make the images comparable which enlarged stars slightly but made the noise in the image obvious. Since it will have likely changed too much to get more data without blurring what I do have I went with this. There is time to try again and again if it keeps changing.

As to the change, it appears to me that the cloud itself is not changing significantly, it is how dust around PV Cephi casts shadows across it that are the cause of the change. It seems the same features are always there, just illuminated differently. A mono animation taken every few days might be interesting. Unfortunately, so far this year I don't have the skies to try that.

To the upper left of the nebula is a small highly elongated nebulous patch. The lower section is the Herbig Haro object #415. I found no separate designation for the upper longer section. It too may be the HH object but the coordinates for it at SIMBAD point to the lower section. The dark nebula in the lower right is LDN 1155C, part of the larger LDN 1155 outside of my image. What few galaxies are in the image and listed at NED are listed only by coordinates so I didn't make an annotated image. One is available at my 2013 post http://www.spacebanter.com/attachment.php?attachmentid=5155&d=1402648490 .
My full image from 2011 can be seen at: http://www.spacebanter.com/attachment.php?attachmentid=4269&d=1347392450 . My 2011 image was with my old filters that tended to put a blue cast I'd not learned to remove. I should reprocess it.

I've attached a crop of the nebula as seen all four years. For 2011 I used my overly blue sensitive filters but the same new ones for the last three years. Still, due to transparency issues, there's a color shift I'm not happy with. The comparison images are at about 0.8" per pixel though due to temperature differences between the nights there is some difference in image scale evident as I didn't compensate for temperature.

Data for 2015
14" LX200R @ f/10, L=5x10' RGB=2x10', STL-11000XM, Paramount ME