jeff heck
professor emeritus
Reged: 01/16/06
Posts: 629
Loc: stl,mo.
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I tried twice last week but could not find M1-92. The Crescent nebula was easy to see at 50x with a UHC filter. I tried variuos mags. with and without both UHC and OIII but no luck on the Footprint nebula. Any tips?
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"Hey, Mr. Spaceman.
Won't you please take me along, I won't do anything wrong.
Hey, Mr. Spaceman.
Won't you please take me along for a ride."
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sgottlieb
sage
Reged: 07/22/07
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Quote:
I tried twice last week but could not find M1-92. The Crescent nebula was easy to see at 50x with a UHC filter. I tried variuos mags. with and without both UHC and OIII but no luck on the Footprint nebula. Any tips?
A couple of things to consider --
The Footprint a very young "proto-planetary" or post-asymptotic giant branch (AGB) star with a low-excitation spectrum. So it doesn't respond to an OIII or UHC filter and just go with the unfiltered view.
The Footprint is *very* small -- under 10 arcseconds -- so it will probably appear stellar below 200x and even at 200x-250x will just appear as a soft "star". Fortunately, the object has a high surface brightness so you can use high powers if the seeing permits. At 300x, the "heel" can be resolved as a separate extension.
Here's how it appeared in my last observation using an 18-inch at various magnifications from Fremont Peak.
18" (10/13/07): easily noticed in the field at 225x as a slightly soft "star", just 30" east of an orange mag 9.8 star. This star is the brightest in a small string of 3 stars oriented NW-SE. At 300x appeared only 4" in diameter with a very small, faint extension to the SE ("heel" of the Footprint). At 565x, the "heel" sometimes appeared detached, though was generally just a very low surface brightness swelling towards the SW.
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Steve Gottlieb
18" f/4.3 Starmaster
Adventures In Deep Space
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jeff heck
professor emeritus
Reged: 01/16/06
Posts: 629
Loc: stl,mo.
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Thanks for the info, Steve. From your report and scope size I might have problems seeing this object under all but pristine conditions. I will keep trying, the hunt is on! 
--------------------
"Hey, Mr. Spaceman.
Won't you please take me along, I won't do anything wrong.
Hey, Mr. Spaceman.
Won't you please take me along for a ride."
The Byrds "Mr. Spaceman" 1966
XT10 classic
TV ep's
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sgottlieb
sage
Reged: 07/22/07
Posts: 389
Loc: SF Bay area
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Quote:
Thanks for the info, Steve. From your report and scope size I might have problems seeing this object under all but pristine conditions. I will keep trying, the hunt is on!
Actually, the V magnitude is close to 12.0 so it's really not a very faint object. The trick is identifying a tiny object buried in a rich Milky Way field!
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Steve Gottlieb
18" f/4.3 Starmaster
Adventures In Deep Space
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David Knisely
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Reged: 04/19/04
Posts: 8803
Loc: Beatrice, Nebraska
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Re: the Footprint. This one is tiny and emits light over a wide spectrum. Filters didn't help much with it (UHC helped maybe a tiny bit). You have to have a good atlas that goes down to past 13th magnitude in order to locate it precisely (Megastar was the one I used). I first saw it in a 20 inch f/5 at the Nebraska Star Party last year, but since then, I have tracked it down in my 9.25 inch SCT. My notes say:
Mink 1-92, (9/5/2008): Tiny faint nearly stellar spot next to 12th or 13th magnitude star. Helped slightly by UHC, but not any better than without filters. 298x and 480x show double "puff" very close (in contact?) with W. one possibly a tad larger. Roughly W-E orientation."
Below is a Megastar plot (about 2.1 deg. by 1.2 deg. with north at the top). The star near the upper left corner is magnitude 4.68 Phi (12) Cygni. Clear skies to you.
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David W. Knisely
Hyde Memorial Observatory
http://www.hydeobservatory.info
Prairie Astronomy Club
http://www.prairieastronomyclub.org
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jeff heck
professor emeritus
Reged: 01/16/06
Posts: 629
Loc: stl,mo.
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Thanks for the chart, David. I will invert and print it for the next time out. I only have a Pocket Sky Atlas so that really helps.
--------------------
"Hey, Mr. Spaceman.
Won't you please take me along, I won't do anything wrong.
Hey, Mr. Spaceman.
Won't you please take me along for a ride."
The Byrds "Mr. Spaceman" 1966
XT10 classic
TV ep's
|
Dain
Carpal Tunnel
Reged: 03/24/05
Posts: 2047
Loc: N.Y. Adirondack Mnts. NGC 4565...
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The Footprint is often listed as a planetary nebula but is actually a reflection nebula, correct?
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Best,
Dain
Adirondack Mountains (my true dark sky site)
@ Cedar River Flow
Local Site
Clear Skies?
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David Knisely
Postmaster
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Quote:
The Footprint is often listed as a planetary nebula but is actually a reflection nebula, correct?
It is thought to be a "proto-planetary" nebula that might eventually become a full-blown planetary. However, much of its light is from scattering off the gas and dust rather than from emission lines from the gas. Here is an early paper on the spectrum of the object:
The Spectrum and Structure of Minkowski's Footprint
Clear skies to you.
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David W. Knisely
Hyde Memorial Observatory
http://www.hydeobservatory.info
Prairie Astronomy Club
http://www.prairieastronomyclub.org
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CaptainTruss
super member
Reged: 07/10/06
Posts: 153
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Quote:
The Footprint is often listed as a planetary nebula but is actually a reflection nebula, correct?
It is a proto-planetary nebula. A planetary nebula in it's young stage. It's bi-polar, which explains it's shape.
They do not respond to nebula filters yet, don't use any. The way you can pull them out is to print a good FOV chart or use a good atlas program such as Skytools or Megastar. In my 14.5" I could see it's cigar shape at 328x. I recommend high power for any proto-planetary nebulas to tell them from surrounding stars.
Check out the november observing list on my website www.avertedvision.net. I have 1 proto PN on there, Hubble(Hb) 12.
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Dain
Carpal Tunnel
Reged: 03/24/05
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Loc: N.Y. Adirondack Mnts. NGC 4565...
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I'm probably going to need explainations, but I'm confused as to why Wiki mentions " a proto-planetary nebula emits strong infrared radiation, and is a kind of reflection nebula."
A protoplanetary nebula (PPN) is an astronomical object which is at the short-lived episode during a star's rapid stellar evolution between the late asymptotic giant branch (LAGB) phase and the subsequent planetary nebula (PN) phase. A PPN emits strong infrared radiation, and is a kind of reflection nebula. The exact point when a PPN becomes a planetary nebula (PN) is defined by the temperature of the central star.
Clear Skies to All!
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Best,
Dain
Adirondack Mountains (my true dark sky site)
@ Cedar River Flow
Local Site
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peter k
super member
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Nice site, CaptainTruss. And your username cracks me up.
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Jeff Young
Post Laureate
Reged: 08/04/05
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Loc: Ireland
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Dain --
As I understand it, when the star first expels its outer layers into a proto-planetary nebula the star is still quite cool. We see the outer layers due to reflected light from the star itself. Because reflected light is broad-spectrum, it doesn't respond well to filters.
Later, when the central star heats up, its strong radiation excites the gas in the nebula causing the gas to emit light. That light is narrow-spectrum (Halpha, Hbeta, various O lines, etc.) and therefore responds well to filtration.
This boundary between reflection and emission is the boundary between proto-planetary nebula and planetary nebula.
At this point I'm out of my depth, but I expect the infrared radiation they're speaking about during the early phase is too long a wavelength to excite the hydrogen or oxygen in the gas, and so doesn't cause emission.
Cheers,
-- Jeff.
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Nikon 18x70s / UA Millennium Colorado:
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Jeff Young
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Oh, and back to the Footprint itself:
Quote:
M1-92 Minkowski's Footprint 8/21/2009 23:30 UT; Pickering 7, NELM 6, SQM 20.6
400mm Mak-Cass @ 600x
Wow, is this one tiny! Completely stellar in appearance up to 335X; hints of elongation at 450X; with bipolar nature only apparent at 600X. Looks like a fairly fuzzy notched double with the ESE component about 1/3 to 1/2 the size of the WNW component.
-- Jeff.
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Nikon 18x70s / UA Millennium Colorado:
Solarscope SF70 / TV Pronto / AP400QMD Coronado SolarMax40 DS / Bogen 055+3130
APM MC1610 / Tak FC-125 / AP1200GTO Tak Mewlon 250 / AP600EGTO
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David Knisely
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Reged: 04/19/04
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Yes, when the central star finally forms a "pre" white dwarf star, it isn't very bright in the visual part of the spectrum. However, its ultraviolet energy output is very high, allowing that light to excite the gas in the expelled shell(s) causing it to glow. Also, the gas in the shell has to disperse a little and get somewhat rarefied for the OIII emission to develop, as once excited, you kind of have to "leave the Oxygen atoms alone" for a while and not bother them via intensive collisions or interactions in order for the "forbidden" Oxygen III transitions to take place. Clear skies to you.
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David W. Knisely
Hyde Memorial Observatory
http://www.hydeobservatory.info
Prairie Astronomy Club
http://www.prairieastronomyclub.org
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sgottlieb
sage
Reged: 07/22/07
Posts: 389
Loc: SF Bay area
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Quote:
I have 1 proto PN on there, Hubble(Hb) 12.
I haven't run across Hb 12 being listed as a PPN (proto-planetary) and it's listed as a true planetary in Kohoutek's 2001 version of the Catalogue of Galactic Planetary Nebulae. Do you know if the status has changed?
Here are a few additional interesting objects with nicknames that are often listed in the PPN category --
Red Rectangle (CRL 915) in Monoceros
Frosty Leo Nebula (IRAS 09371+1212) in Leo
Boomerang Nebula (ESO 172-007) in Centaurus
Butterfly Nebula or Minkowski's Butterfly (M 2-9) in Ophiuchus
Egg Nebula (CRL 2688) in Cygnus
Rotten Egg Nebula (OH 231.8+4.2) in Puppis
Garden Sprinkler Nebula (He 3-1475) in Sgr
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Steve Gottlieb
18" f/4.3 Starmaster
Adventures In Deep Space
7500+ NGC/IC Visual Descriptions
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Dain
Carpal Tunnel
Reged: 03/24/05
Posts: 2047
Loc: N.Y. Adirondack Mnts. NGC 4565...
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Jeff & Dave,
Thanks so much! I really appreciate your explainations. I *think* I'm understanding it. 
Clear Skies to All!
--------------------
Best,
Dain
Adirondack Mountains (my true dark sky site)
@ Cedar River Flow
Local Site
Clear Skies?
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Jeff Young
Post Laureate
Reged: 08/04/05
Posts: 4333
Loc: Ireland
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Certainly, Dain.
And thank you Steve for the target list. I had the Red Rectangle, Minkowski's Butterfly and Egg Nebula, but the others are new to me.
Cheers,
-- Jeff
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Nikon 18x70s / UA Millennium Colorado:
Solarscope SF70 / TV Pronto / AP400QMD Coronado SolarMax40 DS / Bogen 055+3130
APM MC1610 / Tak FC-125 / AP1200GTO Tak Mewlon 250 / AP600EGTO
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sgottlieb
sage
Reged: 07/22/07
Posts: 389
Loc: SF Bay area
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Quote:
And thank you Steve for the target list. I had the Red Rectangle, Minkowski's Butterfly and Egg Nebula, but the others are new to me.
Cheers,
-- Jeff
All the objects in my proto-planetary list are in SIMBAD under their nicknames except for the "Garden Sprinkler Nebula". You can just google the name for images (you'll see where it gets its nickname) and other info. This object can be found in SIMBAD under the alias "Hen 3-1475".
And there are more photogenic PPN. How about the "Cotton Candy Nebula" and the "Silkworm Nebula"? They are the top two images in this Hubble mosaic.
--------------------
Steve Gottlieb
18" f/4.3 Starmaster
Adventures In Deep Space
7500+ NGC/IC Visual Descriptions
NGC/IC Project
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