Object of the Week, December 5, 2021 – HH 1 and HH 2

[Howard B]

Orion
Herbig-Haro objects
RA: 5 36 22.8
Dec: -06 46 03

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Mount Lemmon SkyCenter Schulman Telescope / Adam Block

First, a refresher on what HH (Herbig – Haro) objects are: ( https://tinyurl.com/uwm5tm46 ) and HH 1/2 in particular: ( https://en.wikipedia.org/wiki/HH_1/2 )

I’ve been looking forward to writing his OOTW since early September when I had the completely unexpected pleasure of stumbling across HH 1/2 while observing NGC 1999 from my backyard. In the hour before dawn on September 9, 2021, NGC 1999 had risen high enough in the east so I’d have a decent chance of seeing it fairly well. I was in the final stages of writing an article about 1999 and wanted to get an observation or two from my backyard even though it would be located low in the most heavily light polluted part of my sky. The forecast called for above average transparent skies so I gave it go.

The view of 1999 was fairly dim, and I couldn’t make out its dark cavity, but my eye kept catching on a faint streak of nebulosity nearby. I thought I was imagining it at first, but then the entire area to the southwest of 1999 seemed to filled with faint, lumpy nebulosity! After dawn I came back in the house to confirm the position and orientation of HH 1/2 relative to NGC 1999, and sure enough my sketch lined up with reality.

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I was astonished – this was in the brightest part of my sky with a SQM in the low 19’s. Perhaps the most incredible part is that I was observing with my 8-inch f/4 scope. Evidently, the transparency forecast was a spectacular understatement.

Two mornings later, again just before dawn, I repeated this observation with my 28-inch f/4 scope under an even more remarkably transparent sky, and had an awesome view of both NGC 1999 and HH 1/2. NGC 1999 looked like a photograph, and HH 1/2 were easy, direct vision objects that even showed a little structure. My observing notes:

“The best view of HH1/2 was also at 408x and 545x. 408x showed the greatest extant of nebulosity, while 545x revealed a bit of detail. Pretty awesome! The 408x field of view nicely framed 1999 along with HH1/2 which is why I spent the most time at this magnification. Steady seeing, even at this low elevation (about 20 degrees) made the view even more enjoyable.

I don’t think the atmosphere can get much clearer than it is this morning – just exceptional transparency! The early sunrise colors confirm how clear the air is. (19.94 SQM toward the east, 20.71 straight up)”

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Nebula filters didn’t improve the view at all, and my observations were made without them.

These two observations, and remarkably transparent skies, were exceptional in my experience and have given me food for thought on how darkness, transparency and steady seeing effect views of deep sky objects. These early morning observations are the two best views I’ve had of HH 1/2, and considering how well I saw them with the 28-inch, and that I could see them at all with my 8-inch so low in a light polluted sky, has changed my thinking. It seems to me that transparency is the most important factor in seeing faint deep sky objects – or at least for HH1/2 and NGC 1999.

I’m very interested to read your experiences of observing HH 1/2, and how you think of the interplay between darkness, transparency and seeing.

Give it go, and let us know!

[wvreeven]

Great choice Howard. I have logged NGC 1999 and both HH1 and HH2 with my 20" back in January 2012. They were visible about 50% of the time. That was at 366x.

[Uwe Glahn]

Wow Howard, what a nice choice.

First of all, I can confirm your observation. Transparency comes before darkness. In my case, a brighter mountain sky shows much more than a dark sky in the plains. Because of that I'm a critic of using a SQM and than conclude the "sky quality". The SQM is only a light meter which often doesn't show what to expect in the telescope.

To HH 1 und HH 2. I spotted both objects first around 15 years ago together with my former observing buddy with our old 16-inch. In contrast of your observation, we both uses an UHC filter to get the best results.

In a quick and dirty translation I wrote:
HH 1: 16", 257x, UHC, NELM 6m5+; fainter HH object, 2.3' SW of NGC 1999, stellar appearance, steady visible with averted vision
HH 2: 16", 257x, UHC, NELM 6m5+; brighter HH of the pair, 4' S of NGC 1999, laminar and around 3:2 N-S elongated, direct vision object even without the UHC filter

I don't find any notes about the observation with a 10-inch, but I remember it very good that we both could see HH 2 easily and HH 1 with difficulties.

sketch: 16", 257x, UHC, NELM 6m5+, Seeing III
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home (http://www.deepsky-visuell.de/Zeichnungen/Herbig_Haro_1_2.htm)

[kisspeter]

This is a special and very interesting part of the sky. I can contribute another 16" observation from 2016:
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Winter observation from Hungary is usually tricky beacause we don't have mountains and foggy weather is quite common. But sometimes magic happens and the top of the clouds is below the hills. This was not the case when I drew NGC 1999 and HH 1-2. We had only average conditions. HH 1 was a very faint detailless averted vision object, barely visible. HH 2 was somewhat brighter, elongated and had a faint starlike core.

[akarsh]

Haha, scooped again! I was going to post this as my OOTW in late December; now I've to think of something else :thinking:. Howard I am amazed you managed to detect the presence of HH1/2 in an 8" scope! :shocked:

I observed HH1 and HH2 at the Okie-Tex Star Party in October 2021, after having failed my previous attempt. I think I understand why I failed earlier -- at least in my 18", the visual extent on NGC 1999 is much smaller than the photographic extent, as is typical of many objects. So HH2 is further out from the notch of NGC 1999 than a POSS image would lead me to believe. I instead use the few faint stars in the vicinity of HH2 to locate it. Once HH2 is located, I was able to find HH1.

Here is my report (copy-pasted from the Okie-Tex post I made earlier):

HH2 was significantly easier than HH1, with about 50% holding averted. I roughly estimated its magnitude to be fainter than 14.3mag by defocusing the nearby star Parenago 2402.
HH1 was way fainter, a threshold object of which I got about 4 flashes.
It did not even occur to me to put a filter on these objects.


I thought I had very dark skies on that night at Okie-Tex when I observed these two objects, but I did have a hard time seeing HH1. These objects are supposed to variable on the timescale of a few days or so, but looking at Peter's report, perhaps HH1 is simply a lot fainter most of the time.

Clear Skies
Akarsh