Comet 12P/PONS-BROOKS

Jehin, E. ; Vander Donckt, M. search by orcid ; Hmiddouch, S. ; Manfroid, J. ; Yoshimoto, K. ; Hasubick, W. ; Gonzalez, J. J. ; Gonano, V. ; Yoshida, S. ; O'Meara, S. J. ; Morris, C. S. ; Nakano, S. 

Abstract

E. Jehin, M. Vander Donckt, S. Hmiddouch, and J. Manfroid, STAR Institute, University of Liege, report that they obtained recent observations with the 0.6-m TRAPPIST-South telescope at La Silla and TRAPPIST-North telescope at Oukaimden, Morocco (cf. CBETs 4729, 4840) using broadband and cometary HB narrowband gaseous and dust continuum filters. Preliminary production rates on 2024 Feb. 25 at 10k km using a Haser model: Q(OH) = 1.54 +/- 0.43 x 10E29 molecules/s, Q(CN) = 4.37 +/- 0.28 x 10E26 molecules/s, and Q(C_2) = 7.99 +/- 0.28 x 10E26 molecules/s. The dust-production rates via proxy A(0)f(rho) were estimated by profile-fitting at 10k km and corrected for the phase angle (cf. CBET 5807): A(0)fp(RC) = 17041 +/- 275 cm; A(0)fp(BC) = 14911 +/- 568 cm. Jehin adds that the gas-production rates had been increasing steeply in the previous two weeks, and the coma shows two bright spiral CN jets. C_2 had been rising faster than other species. On Feb. 29.8 UT, an outburst of 0.9 mag was measured in all BVRI filters compared to the previous night.

K. Yoshimoto, Kumage, Yamaguchi, Japan, reports the following total V magnitudes and coma diameters (obtained with a 0.20-m f/8 Ritchey-Chretien reflector + CCD in January and March, and with a 0.08-m f/4.3 refractor + CMOS camera in February): Jan. 14.41 UT, 8.7, 7'.4; 28.41, 8.4, 5'.5; 29.41, 8.0, 5'.9; Feb. 2.41, 8.0, 7'.8, 10.43, 7.4, 7'.1 (40' tail in p.a. 355 deg); 12.43, 7.0, 7'.6 (1.5-deg tail in p.a. 7 degrees); Mar. 10.43, 6.0, 9'.2.

Selected visual total-magnitude and coma-diameter estimates: 2023 Nov. 8.72 UT, 11.5, 1'.1 (W. Hasubick, Buchloe, Germany, 44-cm reflector); 11.71, 8.9, 2'.6 (Hasubick); Dec. 14.81, 9.5, 5' (J. J. Gonzalez, Leon, Spain, 0.20-m reflector); 2024 Jan. 19.76, 8.1, 3.1' (V. Gonano, Udine, Italy, 10x50 binoculars); 27.72, 8.0, 5'.5 (Gonano); 28.74, 8.5, 3'.3 (Hasubick, 10-cm refractor); 30.72, 8.1, 6' (Gonano); Feb. 4.72, 7.7, 6' (Gonano); 12.39, 8.0, 4' (S. Yoshida, Ibaraki, Japan, 0.40-m f/4.5 reflector); 16.41, 7.8, 8' (Y. Nagai, Saitama, Japan, 20x100 binoculars); 17.43, 7.0, 6' (Yoshimoto, 20x100 binoculars); 19.82, 7.4, 8' (Gonano); 26.42, 6.7, 7' (Yoshimoto); 27.43, 7.2, 6' (Nagai); Mar. 1.01, 5.7, -- (S. J. O'Meara, Lexington, MA, USA, 10x50 binoculars); 2.40, 5.7, 12' (Yoshimoto, 8x42 binoculars); 5.82, 5.7, 5' (Gonzalez, 10x50 binoculars; 1.2-deg tail in p.a. 10 deg); 9.14, 5.6, -- (C. S. Morris, Fillmore, CA, USA, 10x50 binoculars); 10.44, 5.6, 14' (Yoshimoto); 11.13, 5.2, about 20' (Morris; tail about 5 degrees long); 11.83, 5.3, 5' (Gonzalez, Zamora, Spain, naked eye); 13.44, 5.8, -- (Yoshimoto); 15.44, 5.5 (Yoshimoto).

The following revised orbital elements by S. Nakano (Central Bureau) are from 7681 observations spanning 1883 Sept. 6-2024 Mar. 10 (mean residual 1".6), with corresponding non-gravitational parameters A_1 = +0.30 +/- 0.00 and A_2 = -0.0263 +/- 0.0000. The previous orbit in NK 4930 (and in the ICQ's Comet Handbook 2024) shows residuals of -8" in R.A. and +8" in Decl. for the recent 2024 observations. Astrometry from around 2023 Nov. 16 and 17 are not fitting in this orbit. The comet has passed 1.62 AU from Saturn on 1957 July 29 UT.

Epoch = 1884 Jan. 25.0 TT

T = 1884 Jan. 26.21729 TT Peri. = 199.17783

e = 0.9550365 Node = 255.77477 2000.0

q = 0.7757415 AU Incl. = 74.04076

a = 17.2527107 AU n = 0.01375365 P = 71.66 years

Epoch = 1954 May 18.0 TT

T = 1954 May 22.88479 TT Peri. = 199.02853

e = 0.9548315 Node = 255.89120 2000.0

q = 0.7736660 AU Incl. = 74.17716

a = 17.1284520 AU n = 0.01390359 P = 70.89 years

Epoch = 2024 May 10.0 TT

T = 2024 Apr. 21.12327 TT Peri. = 198.98832

e = 0.9545913 Node = 255.85620 2000.0

q = 0.7807748 AU Incl. = 74.19169

a = 17.1943741 AU n = 0.01382371 P = 71.30 years

Epoch = 2095 Aug. 26.0 TT

T = 2095 Aug. 11.10082 TT Peri. = 198.89080

e = 0.9548918 Node = 255.92870 2000.0

q = 0.7836218 AU Incl. = 74.04384

a = 17.3720510 AU n = 0.01361217 P = 72.41 years