3 Attachment(s)
A Messier marathon of sorts
Notes from the last weekend’s outing with my 16” to our remote dark site. Although I observed all Messier galaxies in detail over the last years, Messiers of other types have long been neglected in my observing – most since the time of my Messier marathon four years ago. So last week I decided to reobserve as many of them as possible during what was forecasted to be two clear, moonless weekend nights. I did not want to re-run the marathon in the conventional sense, but observe at my usual pace (unhurried to glacial), making notes and sketching. It turned out I could only see 13, the skies closing earlier than expected on the second night.
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March 8, 2013. Cherry Springs. 16”. 6” of snow on the field, plowed. 0 to -5 C. 70% humidity. Clear, transparency average with a small area of above average nearby after midnight. Unable to see comet PANSTARRS even with 7x50 Geoma, probably too low even from the airstrip. Zodiacal light quite strong. “Messier marathon”.
M34, OC in Per, is a loose aggregation of perhaps 50 stars that is fully resolved and adequately framed by the Pentax XW40 (45x, 1.5-degree field). It is irregularly but considerably concentrated. NW of the central grouping of several stars is the bright, equal John Herschel double (h1123). SSW of the central grouping is an equally bright but wider Otto Struve double. It is also equal, although the SE component is actually an unresolved double in this triple system (OΣ 44). The color of the doubles is slightly warmer than that of the other stars. Most stars are very slightly bluish, and the doubles are very slightly yellowish white. The cluster is at least 100 My old and 10 ly in diameter, and between 1400 and 2000 ly away. It may contain more than 100 stars. The table diameter is 25’.
M1 is oval (NNW-SSE) at 45x with diffuse edges and little concentration. 225x (Ethos 8 mm) changes the view little. The nebula is large but well framed by the Ethos. There are hints of mottling and some involved faint stars. With time, the mottling is recognized to involve a shallow invagination from the SE and an even shallower one from the NW. The edges of the invaginations may be enhanced, and this is responsible for the “mottling”. The outer part of the edge of the SE invagination, S of a star, at times appears detached. This corresponds to one of the prominent filaments in photos, but also to a group of faint stars. OIII filter at 225x diminishes and shortens the nebula, seemingly mostly from the S.
M38, OC in Auriga, is amply framed by the Pentax. Its core is shaped like a cross whose NW leg is the longest. The rest of the stars are comparatively uniform. All stars are very slightly bluish. To the S near the edge of the Pentax field (1.5 degrees) is the small NGC 1907. It is compact, nebulous, and has numerous stars resolved across the face even at this magnification. An equal wide double, with a separation similar to the cluster, follows it.
M36 just to the SE is similarly fully resolved and amply framed by the Pentax. It is starfish-shaped with the longest ray to the SW. Σ737 on the E edge of the core is nicely resolved at this magnification (10”).
M37 a bit farther SE is similarly well framed. It is much richer (than M38 and M36) and may be incompletely resolved at this magnification (45x). It has a sharply outlined club-shaped core. The “handle” has straight edges and extends E. The head is especially suggesting incomplete resolution; it is the densest part of the cluster. At the base of the club’s head resides the warm-colored lucida.
M35 further SE in Gemini is similarly well framed, about 1/3 of the field of the Pentax. It is only as rich as M34,-6, and -8. It seems fully resolved. It is represented primarily by its core, which is shaped like a scallop shell. The base of the shell points W and is broad and blunt. A bright star resides in its S part. The N and S edges of the shell curve outwards from the base to the broader E edge. The S edge curves vaguely around a lacuna to its S; the N edge is a marvelous arc of many bright stars that get brighter to a lucida on its NE end. The third bright star is near the S end of the broad E edge of the "scallop". To the W in the same field is the compact, nebulous NGC 2158, which is only textured but not resolved.
M44 in Cancer just fits in the field of the Pentax. It is a very loose agglomeration of perhaps 50 stars. Among the brighter stars 3 triangles are noticeable near the center, which are like arrowheads pointing E, W, and N.
M67, the smaller OC in Cancer, is very amply framed by the Pentax. It does have the shape of a Phrygian cap as observed by Smyth. The cap is pointing WSW. To the E of the cap’s base in the void outside the cluster lies the warm-colored lucida. The cap, however, is just the core of the cluster. To its SE it is bordered by a void that itself is shaped like a Phrygian cap – or it is simply extended triangular. It points in the opposite direction (ENE). In it just off the edge of “Smyth’s cap” lies the second bright star. It is much fainter and is similarly warm-colored. The other stars are all cool white or very slightly bluish.
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The Owl
M97, the Owl Nebula, is a sizable soft disk at 45x. It shares the field of the Pentax with M108 to the NW. The pair is wide but acceptably framed. The galaxy is a soft spindle with a starlike nucleus. At 225x in M97, first the asymmetry becomes noticeable, the N half being brighter, then the faint central star, then the sector-shaped eyes, at which time the nebula begins to resemble a partially filled peace sign. OIII filter enhanced the contrast with the surrounding sky, bit does not change the appearance of the nebula. The contrast of the eyes is not enhanced. The central star becomes invisible.
M3 in CVn is s beautiful, large globular at 45x. It is textured across the core, strongly concentrated, and resolved on the periphery. The color is slightly bluish. Some EW elongation is immediately noticeable, which on closer inspection may be attributable to a flattening of the halo from SSE. At 225x in the Ethos, it is beautifully framed and resolved almost to the very center. Despite its sharp concentration, it has at this magnification an irregularly scattered appearance, with a few “rays” of stars. One especially thick ray tapering to the E seems responsible for the E-W elongation at the low power, and a thinner ray extending NNE, which has no counterpart to the SSE or SE, being unresolved at low power, should be responsible for the flattening from the SSE.
M53, a globular in CBe, is compact and softly concentrated at 45x. It is hardly textured. There is a suggestion of a star superimposed on the halo NE of the core. At 225x it is shaped like a crawling starfish, with 3 rays to the NNW and two opposite. It is resolved almost to the center. The NNE ray contains the brightest star, although it is not as bright relatively at this magnification. [04:30]
March 9, 2013. Cherry Springs, 16”. [Again tried for the comet, but the western horizon was compromised by distant clouds.] Continuing the “Messier marathon” from last night.
M79, the globular in Lepus, is small as Messier globulars go, and concentrated at 45x (Pentax XW40). It is not resolved at this magnification. [“Very strongly textured, partially beginning to resolve” is crossed out; in retrospect this was probably the first sign of the deteriorating conditions. After astronomical twilight we were supposed to be on the border of above-average transparency, but the haze seemed to arrive much sooner than predicted.] 225x (Ethos 8 mm) reveals that it has a very large (1/3 field) periphery that is extremely loose. This periphery is fully resolved, with a dozen brighter stars and perhaps twice as many at the threshold. The core is itself concentrated and strongly textured. It is only partially resolved, with a few specs sparkling that don’t seem to be individual stars.
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M78 area
M78 at 45x is a sizable cometary mass “blowing off” a wide double star. NGC 2071 nearby (a William Herschel discovery) is noticeable around the S component of a wider double. 225x brings out NGC 2064 (d’Arrest discovery) and 2067 (a possible Temple discovery). Both remain indistinct however, most of the time, as transparency fluctuates from OK to compromised. NGC 2064 is at times distinct, although the sketch made with the frozen pen still exaggerates its brightness. It shows hints of elongation. NGC 2067 runs parallel to the nearest edge of M78, it is the parallel edges bordering the dark lane in between that make the NGC at all noticeable. The photo shows some stars in the area covered by the NGC nebulosity in this region; it cannot be excluded that these stars, remaining invisible, contribute much or most of the light seen as the NGC visually. There is a small stellar companion embedded just S of the bright star in NGC 2071. The nebula is noticeably cometary to the S of the main embedded star.
[After making these notes around 10:00 I moved to CMa but found the sky intolerably compromised. High haze was moving in waves from the NW and was strangely illuminated. We debated the possible origin of the illumination (high-altitude light pollution, reflection from snow, aurora), because haze at this remote site is normally darker than the sky. I got out my SQM-L and found that the small remaining clear area had 21.6 mag per sq. arcsec – the lower bound for this site – and the neighboring hazy patch was 21.4. Still, the haze undoubtedly was detracting from the brightness of nebulae as well as adding the artificial light, and any half-serious observations had to be abandoned. We chatted on astronomical and quasi-astronomical subjects past midnight, then, seeing no improvement, packed and left.]
