by Steve Gottlieb
I just returned from a week of teaching/observing at San Francisco State's field campus near the Sierra Buttes (by the way, not a sign of a single mosquito all week!). The observing site we use for the class on observational astronomy is at Packer Saddle (7200'), along the Pacific Crest trail. That's as high as you can drive up to the Buttes. You must hike the rest of the way to reach the lookout tower at the peak (8500').
A couple of nights I went after a number of stellar-type planetaries. Most of these little nasties were buried in rich southern Ophiuchus fields (a couple were in barren fields within the Pipe Nebula) and required UHC or OIII filters as well as a photographic finder chart to identify!
| M 2-11 = PK 356+4.1 = PN G356.9+04.5 | 17 20 33.2 -29 00 39 | V = 14.5; Size <11" |
|---|---|---|
| 17.5" (8/5/02): Identified at 141x, although appeared as a mag 14-14.5 "star". Very good response to UHC filter up to 220x where it appeared relatively bright and possibly quasi-stellar. Located 2.1' SSE of a mag 11.5 star. The planetary forms the SW vertex of a small triangle with two mag 14-15 stars ~45" NE and ENE. Without filter the M2-11 is comparable to the brighter of these two stars, but gains 2-3 magnitudes in contrast with the filter. A second fainter planetary, M3-38, is in the field 7' ESE. | ||
| M 3-38 = PK 356+4.2 = PN G356.9+04.4 | 17 21 04.4 -29 03 00 | V = 16.6; Size <5" |
| 17.5" (8/5/02): located just 7' ESE of brighter M2-11, this planetary was quickly centered, but was not visible unfiltered at 220x. Adding a UHC filter, an extremely faint stellar or quasi-stellar object of mag 15.5-16 intermittently popped into view with careful viewing. Located 1.6' SW of a mag 12.5 star at the edge of the dark nebula B256 in southern Ophiuchus. | ||
| M 3-39 = PK 358+5.1 = PN G358.5+05.4 | 17 21 11.4 -27 11 37 | V = 15.3; Size 21"x15" |
| 17.5" (8/7/02): this planetary is situated in a 20' field nearly devoid of stars in the bowl of the Pipe Nebula but was very easy to locate as I drifted from a mag 12 star 10' due east. Also a mag 7.4 is 13' due south and a mag 8 star lies 10' SSW. At 141x and OIII filter, a very faint, fuzzy disc was easily visible with averted. Once identified it could be glimpsed unfiltered. At 263x it was more easily seen without filter as a 10"-15" disc. No contrast gain was noticed at this power using a UHC filter. | ||
| SaWe 2 = PK 358+4.3 = PN G358.8+04.1 = PBOZ 4 | 17 26 59.8 -27 40 27 | Size 70" |
| 17.5" (8/6/02): not seen at 140x or 220x with or w/o filters by scanning around the general location (poor GSC plot of the area). Finally, I referred to the SECGPN to pinpoint the exact location and an extremely faint glow, ~20" diameter, was repeatedly glimpsed at 140x and an OIII filter using averted vision. This object was near my visual threshold though viewed a couple of hours past the meridian. | ||
| M 3-10 = PK 358+3.1 = PN G358.2+03.6 | 17 27 20.1 -28 27 51 | V = 14.2; Size 4"x3" |
| 17.5" (8/6/02): identified at 220x as a mag 14 "star" situated 1.3' W of a mag 11.6 star and 8.5' SW of a mag 8 star. Excellent contrast gain with a UHC and appears within ~0.5 mag of the brighter star just following (gain of ~2 magnitudes). Forms a pair with 16th magnitude H 2-10 5' SE (see observation). | ||
| H 2-10 = PK 358+3.2 = PN G358.2+03.5 | 17 27 32.9 -28 31 07 | V = 16.0; Size 5" |
| 17.5" (8/6/02): not visible with or without OIII filter at 141x or with or without a UHC filter at 220x. At 280x seen using a UHC filter as an extremely faint star or possibly quasi-stellar object. Once it was glimpsed at 280x, I could hold H 2-10 steadily most of the time with concentration. Located 5' SE of much easier M 3-10. | ||
| Th 3-19 = PK 358+3.3 = PN G358.4+03.3 | 17 28 41.8 -28 27 20 | Size stellar |
| 17.5" (8/6/02): not seen at 280x with or without a UHC filter. The exact position was identified using the SECGPN finder chart. | ||
| H 1-16 = PK 0+4.2 = PN G000.1+04.3 | 17 29 23.4 -26 26 04 | V = 15.5; Size 5" |
| 17.5" (8/6/02): Not seen initially scanning a nearly blank starfield at 220x - this planetary is situated within a region of strong absorption in the dark Pipe Nebula! Identified by blinking with a UHC filter and appeared extremely faint, stellar and visible ~90% of the time. One identified H 1-16 could be glimpsed without filter. At 280x, nearly visible continuously w/o filter and adding the UHC there was a modest contrast gain and the planetary was held continuously. Two mag 12 stars lie 9' W. Located 33' WSW of mag 6.1 SAO 185474. | ||
| H 1-17 = PK 358+3.7 = PN G358.3+03.0 | 17 29 40.6 -28 40 22 | V = 15.4; Size <5" |
|
17.5" (8/6/02): easy to identify in the field as located midway between two
mag 9 and 11 stars, 2' N and 2' S, respectively. Visible unfiltered at 280x
as a very faint mag 15 star. Good contrast gain with UHC which makes the
planetary visible continuously.
17.5" (8/5/02): the exact location of this planetary was easy to pinpoint as it is situated at the midpoint of a mag 9.0 star 2.3' N and a mag 10.9 star 2.2' S! Not visible unfiltered. Excellent filter response and visible nearly continuously at 220x and UHC filter. Best view at 263x and UHC filter (7.5 Takahashi LE) and can hold continuously with this combination. Estimate V = 15.5. | ||
| H 1-24 = PK 4+6.2 = PN G004.6+06.0 | 17 33 37.6 -21 46 25 | V = 16.2; Size 9" |
| 17.5" (8/5/02): this faint planetary is located on a line between a mag 10.5 star 4.1' NE and a mag 12.3 star 3.4' SW, so the exact location was easy to pinpoint - but nothing was seen unfiltered at 220x. With the UHC filter, an extremely faint star was intermittently visible, so the visual magnitude is probably no brighter than 16. Looked again carefully without a filter, but the planetary was not seen. | ||
| M 3-12 = PK 5+5.1 = PN G005.2+05.6 | 17 36 22.7 -21 31 12 | V = 14.8; Size 7"x5" |
| 17.5" (8/5/02): identified by blinking with an OIII filter at 141x as a faint stellar object, though not visible unfiltered with certainty. At 220x unfiltered, two faint mag 15 "stars" were visible very close to the position of the planetary. With a filter, the following object "brightened" and was clearly the planetary. Situated near the center of a 3' circle of mag 11.6-13 stars including a mag 11.6 star 1.5' NNW. | ||
| K 1-4 = PK 1+1.1 = PN G001.0+01.9 | 17 40 27.4 -27 01 06 | Size 47"x33" |
| 17.5" (8/6/02): not seen at 100x or 220x without filter. It was possibly glimpsed at 220x with a UHC filter, but the sighting was very uncertain due to a mag 12 star attached on the NE edge. Better view at 100x and OIII filter as a fuzzy, very low surface brightness glow which was confidently seen attached to the star. Perhaps 20"-25" diameter. | ||
| MaC 1-12 = PK 21+2.1 = PN G021.9+02.7 = PM 1-226 = VSP 2-19 | 18 21 21.2 -08 31 42 | |
| 17.5" (8/4/02): identified at 220x using a UHC filter as a very faint, stellar or quasi-stellar object. Once identified could just glimpse without filter as a mag 15.5 "star". There was a good response to a UHC filter and the planetary could be held continuously. Situated in a rich star field, though I was able to star hop over to the position using a GSC-based star chart. Listed in the SECGPN as a possible PNe. | ||
| Pe 1-21 = PK 28-3.1 = PN G028.7-03.9 | 18 57 49.5 -05 27 39 | V = 16.9; Size 10"x8" |
| 17.5" (8/5/02): situated in a very rich star field, so the identification of the exact position was difficult, but finally located ~2.5' N of a close mag 13/14 pair and 3.5' NE of an equal mag 11.5 pair. Not seen with or without filter at 220x. At 280x an extremely faint star or nonstellar knot was intermittently visible at this position with averted vision but difficult to confirm with certainty. | ||
| PM 1-276 = CTSS 1 = PK 043+02.1 = PN G043.3+02.2 | 19 02 17.8 +10 17 31 | Size 14" |
| 17.5" (8/4/02): at 220x and UHC filter, an extremely faint, round disc, ~10" diameter, was intermittently visible perhaps 15% of the time with averted vision. Not glimpsed unfiltered. Located 3.2' N of a mag 10 star and 1' WSW of a pair of mag 12 stars. | ||