TALLY ENTRIES 661-670
|661. COMET FLEWELLING C/2019 D1 Perihelion: 2019 May 11.84, q = 1.578 AU
Over 3 1/2 months have elapsed since I made a "real-time" addition to my comet tally. (The previous entry, which I placed on the tally in late March, was a retroactive addition of an object that I observed almost 20 years ago.) This is the longest period of time that I have gone without a tally addition in 19 years, and it has coincided with a general slowdown in cometary activity (in contrast to the high level of activity that was going on at the beginning of this year).
A lot has happened during these past 3 1/2 months. During the latter part of January Vickie and I traveled to Adelaide, South Australia for three weeks, where I taught a brief course on the "small bodies" of the solar system as a part of the International Space University's Southern Hemisphere Space Studies Program (and also was able to visit my older son Zachary and his girlfriend Karina, who have resided in Adelaide for the past three years while she has been pursuing doctoral studies at Flinders University). Vickie moved in with me at the end of February, making us full-fledged "domestic partners," and she has commenced turning my erstwhile "bachelor pad" into an actual respectable home. Meanwhile, over the fairly recent past I have been busy developing an expanded educational program around the solar system's "small bodies" which I hope to implement next year, and I plan to be making a statement about it (on this website) in a couple of months. Finally, in early March I "celebrated" birthday number 61, and for a birthday present Vickie treated me to a concert by Bob Seger that was held in Albuquerque; during that same trip we visited Santa Fe where I was able to meet with some educators and (together with Vickie) was formally introduced on the floor of the New Mexico State Senate.
The comet that ended the long drought of tally additions was discovered on February 26, 2019, by Heather Flewelling with the ATLAS program in Hawaii, utilizing the ATLAS telescope at Mauna Loa. Although it was too faint to attempt visually at the time, it was nevetheless relatively bright as far as recent survey discoveries go, and two weeks later I sucessfully obtained images of it with one of the Las Cumbres Observatory telescopes while it was still listed on the Minor Planet Center's Possible Comet Confirmation Page. (Unfortunately, the star images were too trailed to allow valid astrometry to be performed.) After the comet's discovery was announced I attempted it visually a couple of times in early April, without success. After the April full moon I made another attempt on the morning of April 29 and suspected a very faint, diffuse, 14th-magnitude object, however the rising crescent moon and some possible thin clouds that moved in prevented me from confirming it. After one day of cloudy weather I was able to observe again, under good sky conditions, on the morning of May 1, and was able to verify my earlier suspect.
Comet Flewelling is traveling in a moderately-inclined orbit (inclination 34 degrees) with an approximate period of 1700 years. It is currently located in western Pegasus and is traveling towards the northeast at 50 arcminutes per day; it passes slightly to the northwest of the "Great Square" during the last week of May and enters western Andromeda during the second week of June, passing three degrees north of the Andromeda Galaxy M31 shortly after mid-July. By that time its motion will have slowed down to somewhat under 20 arcminutes per day and will be turning more directly westward; it reaches its farthest north point (just south of declination +47 degrees) in mid-August, is at its stationary point a week and a half later, and is at opposition in early October. As far as the comet's brightness is concerned, with its being at perihelion in just a little over a week and being closest to Earth (1.57 AU) at the end of May it probably won't get much brighter than it already is, unless it undergoes some sort of post-perihelion brightening (which is not unprecedented for long-period comets that have made previous returns, as is the case with this one). In any event, though, I doubt if I will be following this comet much beyond the end of June.
Comet Flewelling C/2019 D1, as imaged by telescopes of the Las Cumbres Observatory. LEFT: March 13, 2019 -- at which time it was still listed on the Possible Comet Confirmation Page -- from the South African Astronomical Observatory. RIGHT: April 28, 2019 -- a little over 14 hours before I first picked it up visually -- from Siding Spring Observatory in New South Wales.
Despite this latest addition to my tally, the comet activity will likely remain quite low for some time yet, and I don't expect this comet or either of the other two comets I am presently following -- one of which I am already about done with -- to be around for too much longer. It is always possible, of course, that some unexpected bright comets could appear in the not-too-distant future, but otherwise things will probably be pretty slow until I am able to pick up some of the expected comets later this year, including some of those listed on the "Notable Upcoming Comets" page.
CONFIRMING OBSERVATION: 2019 May 1.42 UT, m1 = 14.2, 0.8' coma, DC = 1-2 (41 cm reflector, 229x)
I've commented before in various previous entries about the random nature of appearances of comets in our skies; there are times when cometary activity can be quite high, as was the case during the last few months of last year, and there are times when the activity is very slow, as it is now. A symptom of the present low level of activity was the 3 1/2 months that elapsed before the previous entry to my tally; in general, that slow activity is continuing, but in somewhat of an unusual twist barely over a week elapsed between the addition of my previous entry and my addition of this one.
This particular comet was discovered on September 7, 2018, by Brian Africano during the course of the Mount Lemmon Survey based in Arizona. It was a faint object of about 19th magnitude that initially appeared asteroidal -- hence the name "Lemmon" -- but other observers soon began reporting it as being cometary. It remained faint for the next few months before disappearing into evening twilight, and after conjunction with the sun in late February it began emerging into the morning sky towards the end of March. I made an attempt for it in twilight in early April and didn't see anything, and CCD images that were taken shortly thereafter by other observers indicated that it was still quite faint, even more so than expected. While the viewing prospects were never very good, it now looked like the comet would remain too faint to become visually detectable.
It nevertheless did seem to brighten some over the next few weeks, according to CCD images that I saw. (Unfortunately, it remained too low to access with the Las Cumbres Observatory telescopes.) After the April full moon I made another attempt on the morning of the 29th -- the same morning I first observed the previous comet -- and didn't see anything, but when I tried for it again on the morning of May 8 I was rather surprised to see a faint, diffuse, 13th-magnitude patch of light that moved noticeably against the background stars over a period of 15 to 20 minutes. While there were no real doubts in my mind that I had indeed observed the comet, I was nevertheless delighted to see a CCD image that was posted later that same day by Austrian amateur astronomer Michael Jaeger; he had taken the image a few hours before my visual observation, and it clearly showed the comet as being bright enough to be within my visual range.
The viewing geometry remains poor throughout Comet Lemmon's apparition. It is presently low in the northeastern sky at dawn, being located in western Perseus some six degrees east of the star Theta Cassiopeiae, and is actually at its maximum elongation from the sun, just under 41 degrees. It is traveling towards the east-northeast at slightly over one degree per day, passing through the northern regions of the two members of the "Double Cluster" (NGC 869 and NGC 884) on May 14 and crossing into southeastern Cassiopeia two days later before entering Camelopardalis five days after that (while passing half a degree south of the open star cluster Stock 23 in the process). The comet is closest to Earth (1.92 AU) on May 23, is at its maximum northerly declination (+60 degrees) four days later, and is in conjunction with the sun (38 degrees north of it) just before the end of May. While technically it is an evening-sky object at the time of perihelion passage on June 7, it is buried in twilight at a fairly small elongation, and the elongation keeps shrinking for the next several weeks as the comet recedes from perihelion on the far side of the sun from Earth. It finally becomes accessible in the morning sky during the last two to three months of 2019 but it will likely be very faint by then.
Even though the comet's recent brightening trend suggests it might brighten still further as it approaches perihelion, its poor placement in the sky will keep it from being easily observed. Theoretically, I have about one week to view it before the full moon washes out the morning sky, however since my initial sighting on the 8th the first of a series of rain storms has arrived in southern New Mexico, and the current forecast indicates that the rain may continue throughout the rest of that week. It is thus entirely possible that my sighting of the comet on the 8th will remain my only observation of it; should that be the case Comet Lemmon would become my 33rd "one-time wonder," a group that constitutes almost exactly 5% of all the comets on my tally.
INITIAL OBSERVATION: 2019 May 8.44 UT, m1 = 13.3, 1.3' coma, DC = 3 (41 cm reflector, 70x)
UPDATE (May 12, 2019): Comet Lemmon turns out not to be a "one-time wonder" after all! We've had a brief break in the series of rain storms that are currently traveling across southern New Mexico, and although I had to play a little "dodge-the-clouds" this morning I was able to view the comet again. While my observation was necessarily rather brief, it was enough to see that the comet is slightly brighter and larger than it was four days ago.
It is reasonable to expect that Comet Lemmon might continue brightening as it approaches perihelion early next month, however the decreasing elongation, as well as the full moon which will be arriving in a few days, will likely prevent it from becoming a prominent object. I am quite probably finished with it.
MOST RECENT OBSERVATION: 2019 May 12.44 UT, m1 = 13.0, 1.6' coma, DC = 3 (41 cm reflector, 70x)
UPDATE (May 28, 2019): Comet Lemmon continues to brighten as it approaches perihelion. It is presently near conjunction with the sun -- some 39 degrees north of it -- and recent reports from observers at northern latitudes have indicated a current brightness near magnitude 11 1/2. Although it is not an easy object to access from my latitude, I was nevertheless able to verify these reports for myself last night when I was able to grab an observation of it low above my northwestern horizon, in twilight.
Over the next couple of weeks the comet will gradually climb higher into the northwestern evening sky, and with perihelion passage still a week and a half away it may still brighten a bit further. At the same time, its elongation steadily decreases -- to below 35 degrees by mid-June, and to below 30 degrees a week and a half later -- as it recedes from perihelion on the far side of the sun from Earth, and it will likely not remain visible for much longer. I am hopeful of possibly getting another one or two observations of it before it's gone.
At this time Comet Lemmon is in southern Camelopardalis, five degrees west of the star Beta Camelopardalis and near its maximum northerly declination of +60 degrees. It is traveling just southward of due east at a little over 65 arcminutes per day, and passes one degree south of that star (and 20 arcminutes north of the star pair 11 and 12 Camelopardalis) on June 2.
Curiously, the southern hemisphere has its own version of Comet Lemmon at the moment. Comet Catalina C/2018 W1 was discovered on November 16, 2018 by Greg Leonard during the course of the Catalina Sky Survey based in Arizona; it was initially reported as being asteroidal in appearance but began to exhibit weak cometary activity three weeks later. It remained faint -- never brighter than 17th magnitude -- up until the time it disappeared into evening twilight in early March 2019, however recent reports from observers in the southern hemisphere indicate a present brightness between 11th and 12th magnitude. The comet is traveling in a steeply-inclined orbit (inclination 83 degrees) and passed through perihelion on May 11, 2019 -- only 11 minutes after the perihelion passage of Comet Flewelling C/2019 D1 (no. 661), although there is no relation between the two objects -- at a heliocentric distance of 1.360 AU; it is a Halley-type comet, with an orbital period of 102 years. It is currently located in northwestern Columba at an elongation of 50 degrees (almost due south of the sun) and is traveling towards the east-southeast at close to one degree per day; it passes 50 arcminutes northeast of Comet PANSTARRS C/2016 M1 (no. 629) on June 8.
MOST RECENT OBSERVATION: 2019 May 28.14 UT, m1 = 11.5 (extinction corrected), 2.0' coma, DC = 3-4 (41 cm reflector, 70x; low altitude, twilight)
In this present-day era of the comprehensive sky surveys, it would not seem to be surprising that, on occasion, a comet would be independently discovered by two or more different surveys, and indeed that has happened from time to time. Such was the case with this particular comet, which was independently discovered on November 27, 2018 by Hannes Groeller with the Catalina Sky Survey based in Arizona, and by Brian Africano with the Mount Lemmon Survey, also based in Arizona. (Even though the Catalina and Mount Lemon Surveys are under the same management and utilize the same personnel, their respective survey routines are nevertheless independent of each other.) Although Groeller's discovery preceded Africano's by about half an hour, Africano's report arrived at the Minor Planet Center 20 minutes before Groeller's report did, and in fact the discovery had already been posted on the Near-Earth Object Confirmation Page before the later report arrived, hence the comet was assigned Africano's name.
At the time of its discovery Comet Africano was a relatively dim object of 18th magnitude, located in the morning sky in northern Canes Venatici at a declination of +44 degrees. It is traveling in a steeply-inclined retrograde orbit (inclination 117 degrees) and moved steadily northward after discovery, entering northern circumpolar skies in early January 2019 where it has remained ever since, and passing within 70 arcminutes of the North Celestial Pole shortly before mid-March. I made a couple of unsuccessful attempts for it in late April and early May when it was low in my northwestern sky after dusk, and after it went through conjunction with the sun (47 degrees north of it) during the latter part of May it has now become accessible low in the northeastern sky before dawn. I first successfully observed it on the morning of June 8 as a small and moderately condensed object of 14th magnitude.
Although traveling southward, the comet remains in northern circumpolar skies for another two months. It is currently located in southwestern Camelopardalis at a declination of +63 degrees, slightly to the east of the open star cluster NGC 1502 and the chain of stars known as "Kemble's Cascade" and, being on the opposite side of the sun from Earth, is traveling very slowly towards the south-southeast. As it and Earth travel towards each other and eventually fly past each other, its motion begins to accelerate as it turns more directly southward and then towards the south-southwest. It crosses into Perseus at the end of August and over the course of the subsequent month plunges through that constellation, Andromeda, eastern Pegasus, and western Pisces; it is at opposition in mid-September and on September 27 it passes 0.49 AU from Earth, at which time it will be traveling at slightly over 3 1/2 degrees per day. Based upon its present brightness the comet should be somewhere between 9th and 10th magnitude at that time, and thus possibly detectable with ordinary binoculars.
Following its passage by Earth, Comet Africano continues its general southward plunge although it starts to slow down, crossing into eastern Aquarius in early October (and passing 20 arcminutes southeast of the Helix Nebula (NGC 7293) on the 11th) and then Piscis Austrinus and finally into Grus by month's end. It reaches a stationary point in mid-November, by which time its declination will be -42 degrees and its motion will have dropped to just over 10 arcminutes per day; it will likely have faded to about 12th magnitude by then. The rest of the comet's apparition is rather anti-climactic as it continues traveling slowly towards the south-southeast, and by the end of 2019 it will be at a declination of -46 degrees before passing just less than half a degree north of the star Alpha Gruis (Alnair) at the end of the first week of January 2020. By that time it will no longer be accessible from my latitude and in any event will likely have faded beyond the range of visual detectability.
The overall comet activity has been rather quiet for the past few months, and although it probably won't become especially bright, Comet Africano's appearance should nevertheless liven things up at least a little bit, together with a few other inbound comets that I may be picking up within the not-too-distant future. Meanwhile, I've got a couple of interesting efforts in the works -- including the "small bodies" educational program that I've mentioned in previous entries -- and hope to make some public announcements about these shortly.
And on the personal side . . . I've recently learned that I've become a grandfather, of sorts: my younger son Tyler has recently begun dating a young lady (Sara) who has a six-year-old daughter (Avery) from a previous relationship. Given the circumstances, I suppose that "grandfather" might be a bit of a stretch, but this is a phase of life that I was expecting sooner or later, and in any event I wish the new couple all the best.
INITIAL OBSERVATION: 2019 June 8.43 UT, m1 = 14.0, 0.8' coma, DC = 4 (41 cm reflector, 229x)
Exactly fifty years ago this month, i.e., in July 1969, the Apollo 11 mission successfully completed humanity's first manned landing on the moon and safe return to Earth. As a child growing up in the 1960s I was totally caught up in the entire "rush to the moon!" effort, and I vividly remember, at the age of 11, watching the Apollo 11 moonwalk on July 20 with my family on the black-and-white TV we had in our living room. I still have the photographs I took from the TV screen during the moonwalk.
At the time I honestly believed I was seeing a preview of my own future. That obviously did not happen, of course, one major reason being that, once the political goals had been accomplished, American society by and large lost interest in the effort. (Not me, certainly; I continued avidly following the remaining Apollo missions.) The career and other personal decisions I made at a young age -- including what in hindsight are obvious mistakes -- played a non-trivial role as well. Still, I have had what by many accounts could be considered a reasonably decent career and have made my own contributions to the exploration of space, including my involvement in the radio science experiment of Voyager 2's encounter with Uranus in 1986. My doctoral dissertation continues to be cited on a fairly regular basis, and the comet and asteroid observations I have made over the years -- including some mentioned in these pages -- have also contributed to the cause, including assisting in some spacecraft missions. And, certainly, there was that comet discovery I managed to make . . .
LEFT: Neil Armstrong's first step onto the lunar surface, July 20, 1969. I took this photograph directly from the TV broadcast of the moonwalk. RIGHT: The Apollo 11 landing site on the Sea of Tranquility, as imaged from 15 miles (24 km) above the lunar surface by NASA's Lunar Reconnaissance Orbiter on November 5, 2011. Image courtesy NASA/Goddard Space Flight Center/Arizona State University.
And now, 50 years after Apollo 11 . . . I am able to mark the occasion by making another addition to my comet tally, although in keeping with the overall current low level of comet activity this is another faint one. The discovery comes courtesy of the LINEAR program in New Mexico, which dominated comet and asteroid discoveries during the first few years of the 21st Century and which I mentioned several times in "Countdown" entries. The LINEAR program as it then existed closed down near the end of 2012, with its final comet discovery being C/2012 X1 (no. 533); as I comment in that object's entry, LINEAR had by that time 214 named comet discoveries to its credit. During the middle years of this decade, meanwhile, LINEAR tested a 3.5-meter "Space Surveillance Telescope" (SST) from an adjacent site on White Sands Missile Range and discovered six additional comets, two of which I've seen (C/2016 A8 (no. 602) and this one); together with two previously-discovered "asteroids" found by LINEAR that exhibited cometary activity on subsequent returns, LINEAR's comet discovery total now stands at 222. I've managed to observe 69 of these comets, and after including multiple returns of short-period comets the name "LINEAR" now appears 72 times in my tally, which is not only far and away first place among comet names on my tally, but constitutes almost 11% of all the comets on it. The SST, meanwhile, is scheduled to be deployed near Exmouth, Western Australia, within the not-too-distant future, and presumably we might be seeing more LINEAR-discovered comets before much longer.
This particular comet is LINEAR's final comet discovery (as of now, anyway). LINEAR discovered it as long ago as January 26, 2017, at which time it was a dim 18th-magnitude object located 7.15 AU from the sun and slightly over two years away from perihelion passage. Traveling in a moderately-inclined direct orbit (inclination 54 degrees), Comet LINEAR gradually traveled southward from its discovery location (declination -24 degrees) and entered southern circumpolar skies in early 2018, where it remained for the next twelve months and reached a peak southerly declination of -68.7 degrees in mid-November. I am not aware of any visual observations that might have been attempted throughout this time, but CCD reports I have seen suggest a brightness near 15th magnitude during the latter months of 2018.
I had hopes of attempting Comet LINEAR when I was in South Australia during January/February of this year, but it was near conjunction with the sun (43 degrees south of it) at the time; furthermore, this was in a bad direction -- directly into the skyglow of Adelaide -- from Stockport Observatory (where I had a couple of observing sessions), and thus I was never able to make such an attempt. As the comet gradually traveled northward and began emerging into the southern hemisphere's morning sky I was somewhat surprised not to read of any observation reports, so in early May I took some images with the Las Cumbres Observatory, and saw that it was in fact quite prominent and well-developed. After I posted this in relevant forums, I did start to see some scattered visual observation reports from observers in the southern hemisphere that indicated the comet was around 14th magnitude.
Reports since then have nevertheless continued to be few and far between. Meanwhile, by mid-July the comet had finally become accessible from my latitude, very low in my southeastern sky just before the beginning of dawn, and I made my first attempt for it on the morning of July 11 but couldn't see anything that was convincing. I took another Las Cumbres image shortly thereafter, which showed that the comet remained prominent and well-developed, and suggested that I hadn't missed it by much. After clouds and rain the following morning, on the morning after that -- the 13th -- with good sky conditions and armed with the knowledge of exactly where to look and what to look for, I successfully detected the comet as a very faint, small, moderately condensed object of 14th magnitude. With its being located only two to three degress above the range of hills to my south it was very close to the limit of visibility.
Las Cumbres Observatory images of Comet LINEAR C/2017 B3. LEFT: May 5, 2019, from Cerro Tololo Inter-American Observatory in Chile. RIGHT: July 11, 2019, from Siding Spring Observatory in New South Wales.
Comet LINEAR is currently located in northern Phoenix 1 1/2 degrees south-southeast of the star Kappa Phoenicis at a declination of -45 degrees and, having passed through its stationary point at the beginning of July, is now traveling slowly towards the west-southwest; it passes 20 arcminutes south of the star Epsilon Phoenicis on August 12 and reaches a maximum southerly declination of -46.1 degrees three days later before gradually turning towards the northwest, crossing into eastern Grus in mid-September and crossing north of declination -40 degrees one month later. Meanwhile, the comet is nearest Earth (3.48 AU) on August 20 and is at opposition in mid-September.
I don't expect much change in the comet's brightness over the next few weeks, and although it will remain quite low above my southern horizon it should climb marginally higher as it approaches opposition, and thus I expect to be able to observe it for at least that long. After that, however, it will likely be fading as it recedes from both the earth and the sun, and I doubt if I'll be able to follow it for much longer.
In addition to all the Apollo 11 retrospectives going on right now, events are happening, both here at home and in the wider world. For the past few months I have been putting together an educational program, "Ice and Stone 2020," which I formally announced at the beginning of July and about which I'll have more to say in a subsequent entry. One of the "wider world" events that I have found interesting is the series of earthquakes that struck Ridgecrest, California earlier this month, including the 7.1 quake on July 5. Ridgecrest is next to the China Lake Naval Air Weapons Station, and during the latter part of my Navy years in the early 1980s I made regular visits to China Lake as a part of my job. I would usually take my telescope -- the Meade 8-inch (20 cm) Newtonian reflector that I still have and use on occasion -- with me, and observe from a desert site south of Ridgecrest. A few of the comet observations on my lifetime list were made from this site during the course of these trips.
INITIAL OBSERVATION: 2019 July 13.43 UT, m1 = 13.8 (extinction corrected), 0.5' coma, DC = 3-4 (41 cm reflector, 229x)
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