CentaurZ

Comet C/2023 P1 (Nishimura) is currently at magnitude +9.3. Based on JPL parameters, it might peak at magnitude +5.4 when it reaches perihelion at 0.2252 AU on 2023 SEP 17.  

The comet will pass 0.8378 AU from Earth on 2023 Sep 12. It was discovered 2023 AUG 11 by H. Nishimura in Japan.

The explanations have been great, so I can add very little. There are also miniscule true librations of only a few minutes in lunar latitude and longitude. Often writers refer to the Moon's elliptical orbit as the cause of certain things. Actually, they are due to the Moon's eccentric (Earth off-center) orbit. The Moon's orbit is close to being circular; the ellipticity is hardly noticeable in a diagram, but the eccentricity is obvious. The two "e" terms are related non-linearly mathematically, but I won't get into that since it's not the point. here.

Below is my rendition of the Moon's upcoming librations beginning each night at 00 Hr CDT (UT-5). It does not consider the 1˚ diurnal librations which would be different for each location on Earth.

Below that is my rendition of the lunar orbit.

On 27/08/2023 at 17:55, Neil_104 said:

I was observing Saturn last night, in preparation for the opposition so I could compare the difference in brightness, aaaaaaaaaand it's cloudy 😐

It's not so much a spike, simply an immediate reversal point. For other planets the magnitude topping is a smooth curving graph.

Here's my graph of Saturn's magnitude.

On 30/08/2023 at 05:02, Cleetus said:

Thanks for posting this. The March 2039 opposition will present the rings at + 00.6 but I assume there must be occasions when the rings are actually "edge on" and invisible in smaller telescopes?

You're welcome. See my chart below.

Your assumption is correct. The next actual "edge on" will be on 2025 MAR 23, although Saturn will be in the predawn eastern sky only 10˚ west of the Sun.

The 2039 APR 02 image below is for the central "edge on" event during that apparition. Due to apparent retrograde motion, 2038 OCT 15 and 2039 JUL 09 will also be "edge on" dates. 

Ringed Saturn currently rises around sunset and achieves opposition from the Sun on 2023 AUG 27, when it is out all night at stellar magnitude +0.4. Its rings will appear tilted at +9.0°.

At the time of its opposition, Saturn’s brightness peaks abruptly, unlike the gentle brightness curve for other planets. This sharp “oppositional flash” is due to a lack of a visible shadow of its rings on the planet, and the lack of ring particle shadows visible on each other, as viewed from Earth.

Photos and descriptions of Saturn and its rings would be welcome additions to this thread.

Brilliant Venus has commenced its apparition in the predawn eastern sky following its inferior conjunction between Earth and Sun on 2023 AUG 13. It will become its brightest on SEP 19, and climb higher before sunrise into late October.

Photos and descriptions of Venus during this apparition would be welcome additions to this thread.

A waxing gibbous Moon will occult (cover) magnitude +0.9 star Antares in Scorpius for observers in much of North America during the evening of 2023 AUG 24. This is the start of a new monthly series that will last until August 2028. The previous series was in 2005-2010. As always, each occultation will only be observable in a specifically defined region.

This month’s immersion will occur on the lunar dark limb, with emersion from the bright limb. Lucky observers on the graze path can witness the star passing through lunar hills and valleys. Those north of the only graze path will see a full occultation.

Photos and descriptions of the occultation would be welcome additions to this thread. If you would like specific occultation or graze predictions for your location, please reply to this post with your longitude, latitude, elevation and time zone.

Below is my graze map for the event.

On 20/08/2023 at 04:54, Mandy D said:

@CentaurZ Sadly, for UK observers, this event appears to be only visible in North America. There appears to be a long list of upcoming occultations on his website, but I suspect they will be for North America, again. Is this correct?

https://curtrenz.com/occultations.html

See my previous post for a detailed answer.  The monthly regions of Antares occultation visibility will hop around the globe, but will almost always miss the UK. My list to which you are referring is for the whole world and not just North America. It can be seen below.

4 hours ago, JuergenB said:

The only visible occultation from Europe in 2023 will be in the afternoon hours of October 18. The angular distance to the sun will be 45°, therefore, depending on the sky transparency, there will be a chance to observe the event.

Indeed, on that date in Europe the Antares occultation should be visible by telescope in daylight. On 2028 JUL 04, the immersion of quite low Antares may be barely visible from Britain but not Germany.

The region of each monthly occultation shifts about a third of the way westward around the globe. During the first half the series it will keep shifting southward, then head back northward during the second half.

Below are my North American graze map and a Chicago data chart for the upcoming occultation,

The magnitude +0.9 star Antares in Scorpius was last occulted (covered) by the Moon during 2005-2010. The next series will commence on 2023 AUG 25 and conclude on 2028 AUG 27.

The long absence is due to the 18.6-year nodal cycle of the Moon’s orbital plane relative to the ecliptic (Earth’s orbital plane). The lunar orbital plane is inclined by 5.15˚ to the ecliptic, and Antares lies 4.57˚ south of the ecliptic. It is only during that period of the nodal cycle in which the southern portion of the lunar orbital plane is in the vicinity of Antares that Antares occultations are possible.

As always, each occultation will only be observable in a specifically defined region. The initial and final portion of the series will only be visible by folks in the northern hemisphere. The long central portion will be seen by those in the south.

Your photos and descriptions of Antares occultations would be welcome additions to this thread.

Asteroid 8 Flora will appear within Aquarius in ecliptical opposition to the Sun on 2023 AUG 26 at magnitude +8.4.

Flora is the innermost large asteroid. It has a mean diameter of 128 km, and was discovered in 1847.

Photos and descriptions of Flora would be welcome additions to this thread.

Near-Earth Asteroid 433 Eros will appear within Aquarius in ecliptical opposition to the Sun on 2023 AUG 12 at magnitude +11.1.

Unfortunately, this will be one of its more distant oppositions at 0.75 AU. In 1975 and again in 2056 the separation is 0.15 AU.

Photos and descriptions of Eros would be welcome additions to this thread.

The first really good night of the series for Sydney, Australia observers will be during the early morning hours of 2023 OCT 31. They should be able to witness nighttime occultation immersions and emersions of Alcyone, Atlas and Merope.

As I noted in my opening post, the initial portion of the series will only be seen by southern hemisphere observers. That means roughly the first year of the series. Perhaps I provided a heads-up a bit too soon for most members, but I believe there are some members from Australia and New Zealand.

1 hour ago, The60mmKid said:

This is interesting. Thank you for posting. Is it possible to see the (fully) new moon with the help of binoculars/a telescope? I haven't thought about this until now...

Not really, if by "fully new moon" you mean at the moment of solar conjunction. The elongation needs to be at least 7˚, which generally requires at least half a day.

1 hour ago, Space Hopper said:

Something to look out for......

Will this only be visible in the US or will it be happening here in the UK as well (ie above the clouds)  ?

As with all occultation series, each monthly event (or in this case grouping) will only be observable in a specific region of the world. Sometimes it will be US, sometimes UK, but most of the times elsewhere.

In the forum here for Observing-Lunar, I'll provide alerts shortly before Pleiades occultations occur for North America or the British Isles.

The six brightest stars of the Pleiades Cluster were last occulted (covered) by the Moon during 2005-2011. The next monthly series will commence on 2023 AUG 09 and end on 2029 AUG 04.

The long absence is due to the 18.6-year nodal cycle of the Moon’s orbital plane relative to the ecliptic (Earth’s orbital plane). The lunar orbital plane is inclined by 5.15˚ to the ecliptic, and the Pleiades are generally between about 4˚ and 4.5̊ north of the ecliptic. It is only during that period of the nodal cycle in which the northern portion of the lunar orbital plane is in the vicinity of the Pleiades that Pleiades occultations are possible.

As always, each occultation will only be observable in a specifically defined region. The initial and final portion of the series will only be visible by southern hemisphere observers. The long central portion will be seen by those of us in the north.

A night in which a number of Pleiades stars are successively occulted the Moon can produce a most enjoyable observing experience.

Your photos and descriptions of Pleiades occultations would be welcome additions to this thread.

Alcyone is the brightest of the Pleiades. Below is a chart I made of its occultation series.

It’s nearly time for my monthly New Moon spotting challenge. I use the term New Moon in its classical sense of one’s first sighting of the Moon after its monthly solar conjunction (Dark Moon). Sharp-eyed observers might attempt to spot the over one-day-old Moon after sunset on Tuesday, July 18^th.  Others should have better luck the following evening.

Photos and descriptions of the young crescent Moon would be welcome additions to this thread.

Pluto will appear within Capricornus in ecliptical opposition to the Sun on 2023 JUL 22 at magnitude +14.9

Photos and descriptions of Pluto would be welcome additions to this thread.

Asteroid 15 Eunomia will appear within Sagittarius in ecliptical opposition to the Sun on 2023 JUL 07 at magnitude +8.8. It is the most massive stony asteroid. Eunomia was discovered in 1851, and has a mean diameter of 268 km.

Photos and descriptions of Eunomia would be welcome additions to this thread.

It’s nearly time for my monthly New Moon spotting challenge. I use the term New Moon in its classical sense of one’s first sighting of the Moon after its monthly solar conjunction (Dark Moon). Sharp-eyed observers might attempt to spot the nearly one-day-old Moon after sunset on Sunday, June 18^th.  Others should have better luck the following evening.

Photos and descriptions of the young crescent Moon would be welcome additions to this thread.

It’s nearly time for my monthly New Moon spotting challenge. I use the term New Moon in its classical sense of one’s first sighting of the Moon after its monthly solar conjunction (Dark Moon). Sharp-eyed observers might attempt to spot the more than one-day-old Moon after sunset on Saturday, May 20th. Others should have better luck the following evening.

Photos and descriptions of the young crescent Moon would be welcome additions to this thread.

A penumbral lunar eclipse will occur during the night of 2023 MAY 05-06. The Full Moon will barely miss the Earth’s umbra, but a shadowing near one limb should become apparent.

This eclipse will not be visible in the Americas or British Isles. However, it should be ideal for observers in India, Australia and southern New Zealand.

Below is a diagram I created. It includes a preview graphic for the upcoming eclipse as seen against an imaginary blue wall to make the shadow fully apparent. The predicted event timings are in AEST (UT+10), but will occur at essentially the same real time for all observers experiencing nighttime. The depicted orientation and Moon altitudes are for an observer in Sydney, Australia.

Photos and descriptions of the eclipse would be welcome additions to this thread.

It’s nearly time for my monthly New Moon spotting challenge. I use the term New Moon in its classical sense of one’s first sighting of the Moon after its monthly solar conjunction (Dark Moon). Sharp-eyed observers might attempt to spot the one-day-old Moon after sunset on Thursday, April 20^th. Others should have better luck the following evening.

Asteroid 7 Iris will appear on the Virgo-Libra border in ecliptical opposition to the Sun on 2023 APR 30 at magnitude +9.6. It is a stony asteroid. Iris was discovered in 1847, and has a mean diameter of 199 km.

Photos and descriptions of Iris would be welcome additions to this thread.