8/28/11 Observing Report – Being Alert and Being Fooled

I paid a visit to Zephyr Ridge Observatory from August 26-28, during which I had one good night of observing and one poor night that was ultimately cut short by cloud cover.  It was very warm during each day, with temperatures exceeding 95° F.  This resulted in pleasant overnight observing conditions.

I continued my survey of challenging planetary nebulae, and bagged a few more from my list.  There were, however, some that I could not see.  These are documented below, and if any of my readers have been able to see these, I would be pleased to hear from you.

My preparations for observing routinely include printing maps from Voyager software, one of several high quality planetarium programs.  I find these printouts more useful than published map collections (I own Uranometria 2000.0, for example) because the field of view and stellar magnitude limits can be controlled to match the specifics of my telescope and eyepiece.  These software-generated maps allow me to zero-in on the precise location of an intended target, and are especially useful – indeed, almost essential – when trying to see something at the very limit of my instrument and my eyes.

But, such maps are only as good as the data used to generate them.  Take the case of He  1-3 (Henize 1-3 or PK059-01.1).  In my previous observing report I stated that I was unable to see this planetary nebula, and opined that I may have been looking in the wrong place.  I thought that the fault was mine, thinking that I made a mistake in interpreting my map.  So, on this trip I tried once again to see this object, and spent considerable time making sure the star field I saw through the eyepiece matched that on my map.  Everything seemed clear this time, and yet there was no nebula at the indicated spot on my map.  But, while carefully scanning the field, I spotted something to the south of the nominal location, and after spending time examining this faint disk, I became quite convinced that I was viewing a planetary nebula, and very likely this was He 1-3.  (See report below.)

The next day I did some research, and found a short article by Franco Sabbadin and Antonio Bianchini that offers evidence that He 1-3 is misidentified in the 1967 Catalogue of Galactic Planetary Nebulae by Perek and Kohoutek (whose “PK” catalog numbers are commonly used to identify such nebula).

Below is a reproduction of a portion of the map generated by Voyager software.  The white arrow points to an icon for the planetary nebula, and this location agrees with the 1967 Perek and Kohoutek catalogue.  The location of the nebula I saw is indicated between the two red lines, and this agrees precisely with the charts provided by Sabbadin and Bianchini in their article.  The distance between the two locations is only about one arcminute, which may seem trivial, but when one is using a high power eyepiece and working hard to see something very faint, such a distance can be important.  (I thank Sabbadin and Bianchini for their work.)

He 1-3 Voyager Chart

The white arrow indicates Voyager's location for He 1-3. The correct location is in between the red lines.

I have written to the support staff at Carina Software (makers of Voyager) to point out this error.  Likewise, I sent the same information to Southern Stars, whose SkySafari software shows the same incorrect location for He 1-3.

While on the subject of misplaced nebulae, I want to highlight my report on my observation of Comet Garradd, which occurred during my second night of observing.  Conditions on that night were poor, with obviously compromised transparency.  Nevertheless, I enjoyed my view of the comet, which was located just west of Zeta Saggitae, a quadruple star system that appears as a double star.  I was surprised by the view of the double star, as it was surrounded by what appeared to be a bright circular nebula.  I was unaware of such a nebula, but I spent quite some time examining it at various magnifications.  I was suspicious of an optical artifact, but it certainly seemed like a nebula, as it was quite steady through each eyepiece I tried, and remained so despite spending about a half hour looking at it.  (There was no dew on my optics.)  Later, I researched Zeta Saggitae and found no mention of a nebula around it, so what I saw remains a mystery.  The most probable explanation is an optical artifact due to moisture content in the atmosphere or very thin loud cover.

I am an experienced observer, but I must admit this sighting had me puzzled for quite some time.  Most likely I was fooled by an atmospheric trick, but if not, I hereby stake my claim for a new nebula!



Observing Report

All observations made with a 20” f/5 reflector.

8/26/2011  9:56 PM
Abell53    Planetary Nebula  Aql  Mag. 16.9
RA 19h06m46s  Dec +06°23’56”  Size 0.52’x0.45’

Good conditions, but a little breezy during this observation.  Current temperature 73F after a hot day in the upper 90s.  It was easy to find the precise location for this nebula using a map from Voyager software. At 212x with no filter, I saw nothing.  With the OIII, however, I could intermittently glimpse a moderate-sized disk using averted vision.  I could not hold it in sight, but I saw it repeatedly, and the size of the disk seemed consistent with the approximately 0.5′ quoted in my notes.  At 98x with OIII, I could also glimpse the disk, but it was easier at 212x.  Gray color.  Central star not seen.  Elusive, but visible.

8/26/2011  10:32 PM
PK059-01.1 or He1-3    Planetary Nebula  Vul
RA 19h48m30s  Dec +22°09’00”

Observed at 363x. Using a map from Voyager software, I was very clear about the field.  The key is a very tight double star, with components of equal magnitude, located just north of the PN.  (For reference, there is a field star very close to the double to the east.)  My map showed the PN about 2 or 3 arcminutes north of the double, located right next to a field star.  I saw this field star, and OIII blinking supported that it is just a star, and there was no sign of a PN next to it.  However, moving further south from there, my map showed a faint field star, and indeed I saw a faint stellar (or fuzzy stellar) object at this location without the OIII.  When I inserted the OIII, the star not only remained in sight, but with averted vision I could detect a small disk, definitely nonstellar.  (For reference, just to SSW of this sighting there is a tiny curving arc of three stars.)  I am convinced that this is the nebula.  No central star or detail – just a small disk visible with averted vision.  I believe Voyager has the PN incorrectly located.

Note:  Subsequent investigation revealed that I was correct.  This is a link to an article that discusses the error, and the correct location shown in the article agrees with where I saw the nebula.

8/26/2011  10:59 PM
PK068-02.1 or He2-459    Planetary Nebula  Cyg  Mag. 9.8
RA 20h13m54s  Dec +29°34’00”  Size 5.0″

This is another failed attempt to see this object.  I am absolutely sure I am looking in the right place, assuming Voyager has this object correctly located.  I tried 212x and 363x with and without OIII, and was unable to see it.

8/26/2011  11:25 PM
Abell74  or PK 072-17.1    Planetary Nebula  Vul  Mag. 12.2
RA 21h16m52s  Dec +24°08’51”  Size 14.52’x13.18′

I was unable to see this.  I am sure I am in the right location, and based on my data it should be quite large.  I tried 98x and 212x with and without OIII, but could only see field stars in the location (which presumably overlay the nebula), but I could not see the nebula.

8/26/2011  11:42 PM
DeHt5  or PK111+11.1    Planetary Nebula  Cep  Mag. 12.5
RA 22h19m36s  Dec +70°56’00”  Size 8.8′

I had no difficulty verifying the correct location using a map from Voyager software.  The nebula is located directly north of a fairly bright star that had a row of three stars to its NNW (nice asterism).   At 98x with no filter I could vaguely glimpse “something,” but it was not convincing.  Inserting the OIII, I was able to detect a vague glow, fairly large, with irregular shape.  I could not make out a complete disk, so possibly I am seeing only a portion of the nebula.  There are field stars superimposed on the nebula, but none of these struck me as a likely central star candidate.

8/27/2011  12:00 AM
M2-56 or PK118+08.1    Planetary Nebula  Cep  Mag. 12
RA 23h56m36s  Dec +70°49’00”

A failed attempt.  I believe I found the correct location, and tried 98x, 212x, and 363x with and without OIII, but saw nothing.  Note that Voyager did not have this object in its database, so I hand-marked the location on the map based on its coordinates.

8/27/2011  12:13 AM
PK118-08.1 or Vy1-1    Planetary Nebula  Cas  Mag. 12.5
RA 00h18m42s  Dec +53°53’00”  Size 5.0″

I confirmed the location with a Voyager map.  This nebula is fairly bright.  At 212x it seemed slightly nonstellar, an assessment I believe is accurate despite the less than perfect seeing.  At 363x I was even more convinced that it was nonstellar.  I blinked an OIII, and surrounding field stars dimmed or disappeared, whereas the PN remained bright.  It appeared white in color.  No central star seen.

8/27/2011  12:28 AM
Simeiz 22 or PK128-04.1    Planetary Nebula  Cas  Mag 12.1
RA 01h30m30s  Dec +58°24’00”  Size 9.0′

I confirmed the location with a Voyager map.  At 98x with OIII filter, I could see a large glow with an irregular border, best seen with averted vision, but I could pick up part of it with direct vision.  There are stars involved in the nebula, but none of these appeared to be the central star.  Once found, I removed the OIII and I could glimpse part of the object, but the OIII offered clear contrast improvement.  Gray color.

8/27/2011  12:42 AM
HDW 3 or PK 149-9.1    Planetary Nebula  Per  Mag. 12.5
RA 03h27m15s  Dec +45°24’20”  Size 9′

A failed attempt.  This object is supposedly large, so I used low power.  I tried 98x with and without OIII, but could not see it.  I verified the location with a Voyager map.

8/27/2011  2:28 AM
PK093-02.1 or M1-79    Planetary Nebula  Cyg
RA 21h37m00s  Dec +48°57’00”

I was able to see this without filter at 98x, 212x, and 363x.  It is somewhat faint, but visible.  Adding an OIII did not offer much enhancement, so I report on the unfiltered view at 363x.  This nebula is of modest size – perhaps an arcminute in diameter – and appeared elongated E-W.  Central star not seen.  Gray color.  With averted vision, I could intermittently pick up a little mottling in the gas, mostly on the east side.   There is a field star just off the west end of the nebula, and a fainter field star touching the east edge of the nebula.  There is a very faint field star north of the halo, a little further out.

8/27/2011 2:57 AM
Abell2634    Galaxy Cluster  Peg  Mag. 13.8
RA 23h38m18s  Dec +27°02’37”  Sep. 68.3′

I found this group at 98x, and panned around the region at both 98x and 212x, and was able to see a number of very faint points of light that were likely galaxies, but which were so faint and unremarkable that I decided to spare myself the job of trying to identify each and every one.  Instead I changed to 363x for close examination of the most prominent grouping within this cluster.  Among these, the brightest member is NGC7720, which had a fairly faint elongated halo and a little brightening in the core.  The remaining galaxies in this area were bounded on the south end by a fairly bright field star, and I could see three galaxies in the WNW direction (IC5341, PGC71987, PGC85577) from that field star, all three being extremely faint.  I could also pick up two more small fuzzy patches, one just east of NGC7720 (apparently NGC7726) and the other SE of NGC7720 (IC5342), both extremely faint.  So, I identified 6 members of this Abel cluster, and spotted several others.  Overall, this group is difficult.

8/27/2011 3:11 AM
NGC288    Globular Cluster  Scl  Mag. 8.1
RA 00h52m47s  Dec -26°35’24”  Mag. 13.8

I viewed this at a very low altitude, and I believe my mirror was partially obstructed by the south wall of the observatory.  But, this globular is fairly large and bright, with a loosely organized halo with a ragged perimeter that extended outward more on one side.  I could resolve two dozen stars, roughly.  The core seemed relatively large and loosely constructed, and I suspect this has a fairly high concentration class.

8/27/2011 3:35 AM
NGC613    Galaxy  Scl  Mag. 10
RA 01h34m18s  Dec -29°25’09”  Size 5.8’x4.6’

The altitude of this object was so low that I believe my mirror was mostly obstructed by the south wall of my observatory.  Indeed, at first I was unable to see this galaxy at all, so I decided to wait while it slowly raised higher (it was nearing transit) and more of my mirror was exposed to the light.  Finally, I was able to see it, although it was a dim view.  I saw a large, extremely faint, elongated hazy patch.  Best seen with averted vision.  There is a field star to the NE, and NNW of that field star is an apparent double, with a bright primary and fainter secondary.

8/27/2011 10:16 PM
C/2009 P1  Comet Garradd    Comet  Sge

Not a good sky this evening.  Some clouds and a threat of more to come.  Visible stars are not “popping.”  Milky Way is visible, but seems muted.  Nevertheless, I was able to see this comet without difficulty, and it is bright and beautiful.  It was located just west of Zeta Sagittae, and both fit into the field of view at 212x.  It has a bright, compact nucleus with a large, roughly circular halo around the core.  Averted vision revealed a faint extension of the halo to the south.  Zeta Sagittae, a quadruple system, appeared as a double star, with a bright primary and much fainter secondary.  Curiously, the double was surrounded by a large circular region of nebulosity that appeared separate and distinct from the comet.  It was quite obvious and striking, but subsequent research showed no nebula around this double.  I suspect I may have seen an optical artifact due to moisture content or a thin cloud.  Strange, as I spent considerable time on this, and the glow did not change during the time of my observation, with the exception of a 10 minute period during which everything was obscured by a passing cloud.

8/27/2011 10:52 PM
NGC6211 Group    Galaxy Cluster  Dra  Mag 14
RA 16h41m28s  Dec +57°47’01”

Still fighting clouds, but this area of the sky was relatively OK.  At 363x I could see a line of four galaxies from SW to NE, ordered in this direction in decreasing brightness.  The first, and brightest, is NGC6211.  It is still rather faint, with a slightly elongated halo and some core brightening.  Moving to the NE, the next is NGC6213, visible with direct vision as just a faint smudge.  Continuing in the same direction, I saw PGC58783 in between two field stars.  It was only visible with averted vision as a very faint fuzzy spot.  Finally, continuing to the NE, I saw another tiny faint fuzzy spot, which I identified as PGC58802.

8/27/2011 11:07 PM
NGC6338 Group    Galaxy Cluster  Dra  Mag. 14
RA 17h15m23s  Dec +57°24’41”

At 363x I could see several members of this group.  The brightest was NGC6338, which had a moderate-sized, slightly elongated halo, and brighter, compact core.  Just to the north of this galaxy, I picked up a small fuzzy spot in between the main galaxy and a close pair of field stars.  This was PGC59943, which also seemed to have a stellar nucleus.  From there, I moved southward and saw NGC6345, which is a tiny hazy spot with a stellar pinpoint in the center.  Very near this, to the south, is NGC5346, which was just a tiny, faint smudge.  Returning to NGC6338, and moving SE from there, there is a row of three field stars, with the middle star being the faintest.  I was able to see a faint patch of light in between the faint middle field star and the last (brighter) field star to the SE.  I identified this as IC1252.  I concluded my tour with this galaxy, even though my map showed a few more (probably very faint, if visible) PGC galaxies in the area.

8/27/2011 11:21 PM
NGC6472 Group    Galaxy Cluster  Dra  Mag 15
RA 17h44m03s  Dec +67°37’49”

A faint group, observed at 363x, and clouds interfered with the observation for one brief period.  The first member I encountered was NGC6463, which was quite faint, visible with direct vision and averted vision revealed a little core brightening with a stellar nucleus suspected.  To the east of this galaxy, I could pick up three galaxies, all extremely faint, forming a small triangle.  These were apparently NGC6470, 6471, and 6472.  I was only barely able to detect these as small fuzzy patches, and each seemed to have a stellar nucleus.  There is a faint field star to the SE of NGC6471, and I could intermittently glimpse another faint spot which may have been NGC6477.  Overall, this is quite a difficult group, made more so by the deteriorating sky this evening.

8/27/2011 11:42 PM
Hickson 85    Galaxy Cluster  Dra  Mag 12.8
RA 18h50m22s  Dec +73°21’00”  Sep. 1.3’

I was able to find the precise location of this cluster using a map from Voyager software.  I was able to see a hazy cloud of light at this location.  I could discern two distinct galaxy cores in this cloud, and a third was glimpsed intermittently with averted vision.  I could not pinpoint the fourth member, and the view of the galaxies I could detect were so faint that I was not able to reliably identify which of the three members I saw.

About Denis

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