Abstract: The possible nova PNV J10251200-5331109 was discovered independently by John Seach (Grafton, NSW, Australia) on 2025 Jun 25.440 UT at unfiltered magnitude 5.7 (DSLR 50 mm f/1.2 lens), and by Andrew Pearce (Nedlands, Western Australia) on Jun 25.515 UT at unfiltered magnitude 5.5 (Canon 800D camera + 85mm f/1.2 lens). Its nature has not been confirmed spectroscopically. COORDINATES (J 2000): RA 10 25 13.88 Dec. -53 31 19.2. PROGENITOR: S. Otero (AAVSO) reports the likely progenitor is blue, large amplitude variability; DECaPS images show 22.2:V. He also notes that the object is nearly superimposed on the 16.8 B mag. galaxy LEDA 96477. PHOTOMETRY: see Justification. View the light curve via the AAVSO Light Curve Generator (Enhanced LCG).
Justification: The AAVSO requests coverage of this object with observations of all types (visual, CCD/CMOS, DSLR, PEP, spectroscopy) and in all filters as it evolves.As good coverage as possible for as long as possible is requested. Spectroscopy is also encouraged where possible. See sections below for cadence and other observing recommendations. The name PNV J10251200-5331109 was assigned when the object was reported to the IAU CBAT Transient Objects Confirmation Page (TOCP, CBAT "Transient Objects Confirmation Page"). ADDITIONAL PHOTOMETRY (reported via the TOCP): 2025 Jun. 25.575 UT, 5.6 visual (A. Pearce); 25.5794, brighter than 7 (lower limit due to saturation; E. Guido and M. Rocchetto using SPACEFLUX 0.35-m f/3.0 reflector and CMOS camera in Perth, W. Australia). Download photometric/spectroscopic observations submitted to the AAVSO via the AAVSO Global Search (Search Data).
This is a crowded field with many variables with their own sequences, so a wide field chart may be too crowded.
I recommend using the binocular option in VSP now that the nova: is bright, to get rif of many comp stars and leave the useful ones.
I created this chart:
Spectroscopic confirmation is still needed! If you can view this field and have even simple spectroscopic equipment, please take a spectrum and report it to AVSpec (AVSpec Submit).
Many thanks, and good observing,
Elizabeth Waagen, AAVSO HQ
In a few hours Ill get spectra in low and high resolutions. But AVSpec submit has no way to identify the nova. It has a fixed list of stars in a combobox
In higher resolution R 5000. spectrum shows a minor absorption Ha line. Unless something weird happened in my identification it is not a nova, nor a supernova. I will investigate more
AVSpec was programmed to require that each observer uploads the spectrum of one of those “standard stars” from the fixed list before they can upload any other spectra. So, unfortunately, the system is going to prevent you from uploading the nova spectrum to AVSpec until you have uploaded a standard star, and an AAVSO staff person has reviewed and approved the standard star (which can take some time).
In the meantime, would you like to upload a plot of the spectrum to the forums? I just updated your forum account so you should have the ability to upload images and attachments now (if not, please let me know).
Thank you so much for taking spectra of this transient!
Great, thank you! I can’t wait see its spectrum!
Is this the ASAS-SN light curve which you mean? It is inaccurate, but I think that is expected; the target is well above the saturation limit for ASAS-SN.
Hi Lauren,
you are retrieving data from an incorrect position, thus the magnitudes will be fainter because the star is outside of the aperture and ASAS-SN is just recomputing the data from the position you provide.
Yesterday I had looked at the light curve and I got:
2460843.59662 2025-06-17.0957943 <17.0 g
2460845.56173 2025-06-19.0610120 <17.0 g
2460845.56297 2025-06-19.0622553 <17.0 g
2460845.56421 2025-06-19.0635001 16.851 g 0.183
2460847.57827 2025-06-21.0776648 9.414 g 0.007 SATURATED
2460847.58077 2025-06-21.0801648 9.241 g 0.007 SATURATED
2460850.55035 2025-06-24.0498979 7.049 g 0.005 SATURATED
2460850.55157 2025-06-24.0511230 7.159 g 0.005 SATURATED
I only kept the brightest points from each night because the others were just strongly saturated data, excepting the very first one, which is also very uncertain because it is at the survey’s limiting magnitude. So most of these points are much fainter than the nova(?) actual brightness.
It is weird that there was no detection on 2460843 in the light curve at the correct position. But all the other magnitudes were much brighter due to the star being at the center of the aperture.
But I agree that it is not weird, it is just ugly because of the saturation.
Cheers,
Sebastian.
PS: there was a report of a brighter V magnitude of 5.01 (corrected because the comp star used has a wrong value) some hours ago from Japan (CBET 5574).
Using Cacella’s color image and visually, manually matching his image with the HyperLEDA image (DSS Colored)… the + marks approximately the location. There is a very faint object near the indicated + position. Might be in both DSS2 Red and DSS2 Blue images as well.
Flat spectrum might it be a galactic SN? Could it be?
The progenitor was strongly variable (4 mag.) and almost colorless. I attach a DECaPS color image in the faint state (mag. 22) that shows the star was rather blue. It is true that variability may play a role because the different color images might be taken when the star had different magnitudes. However, the several detections at maximum (mag. 18) all showed colors close to 0.0. Photometry by Yoshimoto in CBET 5574 showed B-V 0.28.
Were you able to reduce your photometry?
DSLR transformed photometry from Brisbane, Australia last night showed a B-V of 0.352 (SD 0.009). I used 000-BBR-555 as the check star, and determined a B-V of -0.143 (SD 0.032), giving measured minus catalogue B-V of 0.008.
For the stats, n=10 (10 images).
@Spectroscopy We urgently need additional spectra of this object - could anyone who can reach its location ((J 2000): RA 10 25 13.88 Dec. -53 31 19.2) please take data and report here as soon as possible?
Many thanks,
Elizabeth Waagen, AAVSO HQ
