#Comet #Nishimura entered the field-of-view of STEREO's inner Heliospheric Imager (HI-1) on September 17th. This movie shows considerable interaction of the comet's ion tail with the solar wind, along with a possible glancing blow from a coronal mass ejection in the September 22-23 timeframe. Toward the end of the movie, at the start of the day on September 23, the comet appears fainter and the movie appears to slow down. This is due to a pre-planned change in the observing mode for a science campaign unrelated to the comet. The HI-1 image cadence is increased from once every 40 minutes to once every 20 minutes, with a corresponding decrease in exposure time.
https://stereo.gsfc.nasa.gov/gallery/item.shtml?id=stereoimages&iid=238

COMETS LIKE IT HOT: Yesterday, Sept. 17th, #Comet #Nishimura (C/2023 P1) made a close approach to the #sun deep inside the orbit of #Mercury (0.22 AU). The comet survived. Petr Horalek photographed it emerging intact from Mount Lysa in Sabinov, Slovakia:

"Because of the glare of sunset, the comet was not visible to the naked eye, however I was able to photograph it using a 5 second exposure at ISO 1000," says Horalek. "The comet's brightness is hard to estimate. Considering other stars and the comet's location over the horizon, I believe it to be magnitude 2.0 to 2.5."

Horalek's estimate agrees with that of other experienced observers. If the comet remains this bright, it could become easy to see as it recedes from the sun in the evenings ahead.
https://spaceweather.com/

Beautiful #Comet #Nishimura

#Astronomy #Picture of the Day

https://apod.nasa.gov/apod/ap230911.html

#APOD

#COMET AT DAWN: Set your alarm for dawn. There is a bright comet in the morning sky. You probably can't see it with the naked eye, but even relatively short exposures with digital cameras are picking up the starlike head and long tail of Comet Nishimura (C/2023 P1):

"This morning, I was successful in photographing Comet #Nishimura from Zahradne, #Slovakia, where the comet appeared against a slightly cloudy sky," says Petr Horalek. "Its tail is so bright that I could see it easily in my backyard telescope."

Latest estimates of the comet's brightness place it at magnitude +4.5. In a dark sky, this would be visible to the unaided eye, but the morning sky is not dark. Cameras are required to pluck the comet from the twilight of dawn. Many photographers are finding that less than a minute of exposure time is enough for a nice picture. Horalek's photo is a stack of 20 second shots (ISO 800).

The mornings ahead will be more difficult. Comet Nishimura is plunging toward the sun for a close encounter inside the orbit of Mercury on Sept. 17th. Increasing glare will challenge astrophotographers.

"I am truly happy I made it at least once to see this beauty!" says Horalek.

https://spaceweather.com/

www.spaceweather.com

#Comet #Nishimura is plunging toward the sun for a close encounter inside the orbit of Mercury on Sept. 17th. Increasing heat is causing it to brighten rapidly. Latest estimates of the comet's brightness place it at magnitude +4.5.

"This is a 4-second exposure (ISO 1600) from the Cabreja Volcano in Vega de San Mateo on Gran Canaria Island," says photographer Frank A. Rodriguez. "What a nice comet!"

#Comet #Nishimura Grows

#Astronomy #Picture of the Day

https://apod.nasa.gov/apod/ap230909.html

#APOD

#COMET #NISHIMURA AND THE ESKIMO NEBULA: Hyperbolic Comet Nishimura continues to fall into the #solar-system. On Aug. 19th it passed by the Eskimo Nebula. Bill Williams captured the conjunction just above the roof of his house in Florida's Chiefland Astro Village:

"I read about newly-discovered Comet Nishimura (C/2023 P1) on Spaceweather.com, so I decided to take the challenge of capturing it--although my observatory roof slides east and usually blocks low altitude pre-dawn objects," says Williams. "However, I was thrilled yesterday morning when not only did Comet Nishimura show up but also the Eskimo Nebula just 18 arc minutes away!!"

"Astronomical twilight was already underway when I started observing, so to accelerate the capture I took 2-minute LRGB images (binned 3x3)," he continues. "I do not know what percentage of my telescope actually captured photons from the comet, but we got a nice view of the roof gable, too. A thin ion tail also showed up! You don't know unless you try!"

Comet Nishimura is visiting the inner solar system for the first and last time. When it passes by the sun inside the orbit of Mercury on Sept. 18th, the sun's gravity will slingshot it back into deep space. It is expected to become a naked eye object (3rd magnitude) in mid-September.

https://spaceweather.com/

Introducing #Comet #Nishimura

#Astronomy #Picture of the Day

https://apod.nasa.gov/apod/ap230821.html

#APOD

NEW #COMET #NISHIMURA: Astronomers are monitoring a new comet that could become a naked eye-object next month. It is Comet C/2023 P1 (Nishimura), discovered just a few days ago by Japanese #amateur #astronomer Hideo Nishimura. On Aug. 15th just before dawn in June Lake, California, Dan Bartlett photographed it rising in the #constellation #Gemini:

Right now the comet is shining like a 10th magnitude star, a relatively easy target for backyard telescopes. It could become more than 100 times brighter. Forecasters believe the Comet Nishimura will brighten to 3rd magnitude in mid-September when it passes by the #sun inside the orbit of Mercury. This would make it visible to the naked eye from rural areas.

This might be a " #hyperbolic comet." In other words, it appears to have a hyperbolic orbit (e>1) with too much energy to remain inside the solar system. If so, the comet will only visit us once, with the sun acting as a gravitational slingshot, sending the comet hurtling out of the solar system after its flyby. Confirmation awaits additional, more precise measurements of its orbit.

https://spaceweather.com/