21P/Giacobini-Zinner

21P/Giacobini-Zinner
Reported observations:
2012 Jan. 10.78 UT: m1=8.8, Dia.=9′, DC=3/... 20-cm SCT (77x)... Juan José González (Alto del Castro – Aralla, alt. 1720 m., Leon, España) [Amplia y difusa coma elongada. Fin del crepúsculo astronómico. Altura sobre el horizonte: 12º. Cielo muy claro de montaña]
2011 Dec. 22.78 UT: m1=9.3, Dia.=9′, DC=3... 20-cm SCT (77x)... Juan José González (Collada del Fresno – Sierra del Aramo, 1221 m, Asturias, España) [Significativamente más brillante que lo esperado. Amplia y difusa coma externa. Altura sobre el horizonte: 11º. Cielo muy claro de montaña]
2011 Nov. 25.37 UT: m1=12.2, Dia.=1.3′, DC=4... 40.0-cm L f/4.5 (144x)... Seiichi Yoshida (Gunma, Japan)
2011 Nov. 24.38 UT: m1=[12.1... 40.0-cm L f/4.5 (144x)... Seiichi Yoshida (Gunma, Japan)
2011 Nov. 17.78 UT: m1=12.2, Dia.=1.5′, DC=4... 20-cm SCT (133x)... Juan José González (Angliru – Sierra del Aramo, alt. 1540 m., Asturias, España) [Estrellas de comparación de la fotometría TASS. Altura sobre el horizonte: 18º. Cielo muy claro de montaña]
2005 Aug. 06.78 UT: m1=[9.5 ...  40.0-cm L f/4.5 (144x)  ... Seiichi Yoshida (Gunma, Japan) [Several faint stars exist around the position on the chart, so it was uncertain whether the comet was visible or not]
2005 Aug. 05.77 UT: m1=10.8, Dia.=1.6', DC=4 ...  32-cm L (87x) ... Yoshimi Nagai (Gunma, Japan)
2005 Aug. 05.77 UT: m1=10.4, Dia.=2.3', DC=3/ ...  40.0-cm L f/4.5 (144x)  ... Seiichi Yoshida (Gunma, Japan) [Extremely low, and the comet is very faint, so hard to see. Somewhat condensed. It was much easier to see in spring when it located high]
2005 Aug. 02.14 UT: m1=10.4, Dia.=3', DC=4  ...  20-cm SCT (100x)  ...  Juan Jose Gonzalez (Alto del Castro - Aralla, alt. 1720 m, Leon, North Spain)
2005 July 06.11 UT: m1=9.4, Dia.=4', DC=4  ...  20-cm SCT (77x)  ...  Juan Jose Gonzalez (Alto del Trichero - Soto y Amío, alt. 1190 m., León, North Spain ) [Mountain location, very clear sky. Short tail: 0.1 deg. in PA 280 deg.]
2005 July 03.11 UT: m1=9.4, Dia.=4', DC=4  ...  20-cm SCT (77x)  ...  Juan Jose Gonzalez (Alto del Castro - Aralla, alt. 1720 m, Leon, North Spain) [Mountain location, clear sky. Altitude: 11 deg.]
2005 July 02.12 UT: m1=9.7, Dia.=3', DC=4  ...  20-cm SCT (77x)  ...  Juan Jose Gonzalez (Alto del Castro - Aralla, alt. 1720 m, Leon, North Spain) [Mountain location, clear sky. Altitude: 12 deg.. Strong interference from the nearby Moon. Coma enhanced through Swan band filter]
2005 May  18.12 UT: m1=11.2, Dia.=2.5', DC=5  ...  20-cm SCT (100x)  ... Juan Jose Gonzalez (Alto del Trichero - Soto y Amío, alt. 1190 m., León, North Spain ) [After moonset]
2005 May  12.83 UT: m1=11.5:, Dia.=2', DC=3 ... 25x100mm B ... Michael Mattiazzo (Stockport Observatory, South Australia)
2005 May  10.05 UT: m1=11.5, Dia.=1', DC=3 ... 30-cm L(105x) ... Marcin Filipek (Jerzmanowice, Poland)
2005 May  07.76 UT: m1=10.6, Dia.=3', DC=6 ...  46-cmL (68x) ...  Shigeki Murakami (Niigata-ken, Japan)
2005 May  07.14 UT: m1=11.8, Dia.=2.3', DC=5  ...  20-cm SCT (100x)  ...  Juan Jose Gonzalez (Sierra del Aramo, alt. 1230 m, Asturias, North Spain )
2005 May  04.76 UT: m1=11.7:, Dia.=0.8', DC=3 ...  40.0-cm L f/4.5 (144x)  ... Seiichi Yoshida (Gunma, Japan) [Through dim clouds, so probably inaccurate. My observation on May  3 must be accurate.]
2005 May  03.74 UT: m1=12.1, Dia.=1.1', DC=4 ...  40.0-cm L f/4.5 (144x)  ... Seiichi Yoshida (Gunma, Japan) [Already very bright, easy to see. The condensation is not so strong, that is very different from the cases of 78P or 9P at the beginning]
2005 May  02.15 UT: m1=12.3, Dia.=0.8', DC=6  ...  20-cm SCT (100x)  ...  Juan Jose Gonzalez (Sierra del Aramo, alt. 1280 m, Asturias, North Spain ) [Mountain location, very clear sky. Some moonlight interference. Motion checked during a 1-hour period]
1999 Mar. 12.79 UT: m1=13.6, Dia.=0.4', DC=3 ... 44-cm L (156x) ... Werner Hasubick (Buchloe, Germany)
1999 Mar. 12.26 UT: m1=12.5, Dia.=1.1', DC=4 ... 25.6-cm L (84x) ... Nicolas Biver (Dillingham, Oahu, HI)
1999 Mar. 09.25 UT: m1=12.6, Dia.=1.3', DC=5 ... 25.6-cm L (84x) ... Nicolas Biver (Dillingham, Oahu, HI)
1999 Mar. 07.25 UT: m1=13.5, Dia.=1.3', DC=3 ... 25.6-cm L (84x) ... Nicolas Biver (Dillingham, Oahu, HI)
1999 Feb. 17.54 UT: m1=12.2, Dia.=2.1', DC=4 ... 41-cm L ... Andrew Pearce (Dowerin, Western Australia)
1999 Feb. 16.31 UT: m1=11.7, Dia.=1.5', DC=3 ... 25.6-cm L (42x) ... Nicolas Biver (Mokuleia, Oahu, HI)
1999 Jan. 21.55 UT: m1=11.6, Dia.=1.4', DC=3 ... 41-cm reflector ... Andrew Pearce (Nedlands, Western Australia)
1999 Jan. 20.55 UT: m1=11.6, Dia.=1.8', DC=3 ... 41-cm L ... Andrew Pearce (Nedlands,Western Australia)
1999 Jan. 19.74 UT: m1=11.5, Dia.=0.9', DC=3 ... 44-cm L (156x) ... Werner Hasubick (Buchloe, Germany)
1999 Jan. 19.51 UT: m1=11.2, Dia.=2', DC=4 ... 20-cm L(45x) ... Michael Mattiazzo (Wallaroo, South Australia)
1999 Jan. 18.58 UT: m1=11.6, Dia.=1.6', DC=2/ ... 41-cm L ... Andrew Pearce (Nedlands, Western Australia)
1999 Jan. 17.02 UT: m1=11.1, Dia.=1.5', DC=3 ... 25.4-cm SCT (63x) ... Paulo M. Raymundo (Salvador, Brazil)
1999 Jan. 16.54 UT: m1=11.5, Dia.=1.5', DC=3 ... 41-cm L ... Andrew Pearce (Nedlands, Western Australia)
1999 Jan. 14.50 UT: m1=11.0, Dia.=2', DC=3 ... 20-cm L(45x) ... Michael Mattiazzo (Wallaroo, South Australia)
1999 Jan. 14.28 UT: m1=10.9, Dia.=3.0', DC=5, Tail= 4' in PA: 50 deg. ... 25.6-cm L (42x) ... Nicolas Biver (Dillingham, Oahu, HI)
1999 Jan. 12.56 UT: m1=11.4, Dia.=1.8', DC=3/ ... 41-cm L ... Andrew Pearce (Nedlands,Western Australia)
1999 Jan. 12.51 UT: m1=11.0, Dia.=2', DC=3 ... 20-cm L(45x) ... Michael Mattiazzo (Wallaroo,South Australia)
1999 Jan. 12.26 UT: m1=10.8, Dia.=2.7', DC=5, Tail= 4' in PA: 55 deg. ... 25.6-cm L (42x) ... Nicolas Biver (Dillingham, Oahu, HI)
1999 Jan. 11.57 UT: m1=11.3, Dia.=1.6', DC=3/ ... 41-cm L ... Andrew Pearce (Nedlands, Western Australia)
1999 Jan. 11.50 UT: m1=11.0, Dia.=2', DC=3 ... 20-cm L(45x) ... Michael Mattiazzo (Wallaroo, South Australia)
1999 Jan. 11.46 UT: m1=10.6, Dia.=3', DC=3 ... 11-cm L (16x) ... Stuart Rae (Te Awamutu, New Zealand)
1999 Jan. 10.61 UT: m1=11.3, Dia.=1.6', DC=3 ... 41-cm L ... Andrew Pearce (Nedlands, Western Australia)
1999 Jan. 09.59 UT: m1=11.2, Dia.=1.5', DC=3 ... 41-cm L ... Andrew Pearce (Nedlands, Western Australia)
1999 Jan. 07.59 UT: m1=11.0, Dia.=1.6', DC=3/ ... 41-cm L ... Andrew Pearce (Nedlands, Western Australia)
1999 Jan. 07.41 UT: m1=11.0, Dia.=2.5', DC=4 ... 11-cmL (16x) ... Stuart Rae (Te Awamutu, New Zealand)
1999 Jan. 06.73 UT: m1=11.5, Dia.=0.5', DC=5, 44-cm L (63x) ... Werner Hasubick (Buchloe, Germany)
1999 Jan. 06.70 UT: m1=11.0, Dia.=2.0', DC=3 ... 13-cm R (35x+70x) ... Wolfgang Vollmann (Payerbach, Austria)
1999 Jan. 06.54 UT: m1=11.0, Dia.=1.8', DC=4 ... 41-cm L ... Andrew Pearce (Nedlands, Western Australia)
1999 Jan. 06.43 UT: m1=10.3, Dia.=3', DC=4 ... 11-cm L (16x) ... Stuart Rae (Te Awamutu, New Zealand) [Comet continues to change quickly. Has faded significantly since last night.]
1999 Jan. 05.40 UT: m1=9.5:, Dia.=3.5', DC=5 ... 11-cm L (16x) ... Stuart Rae (Te Awamutu, New Zealand) [Uncertainty due to discrepancies in comparison stars and close proximity to a mag 5 star.]
1999 Jan. 04.39 UT: m1=9.3:, Dia.=3.5', DC=4/ ... 11-cm L (16x) ... Stuart Rae (Te Awamutu, New Zealand) [Not entirely confident of observation. Conditions poor and comet hard to see]
1998 Nov. 24.73 UT: m1=9.2:, Dia.=4', DC=4 ... 20-cm L (40x) ...  Alexandr Baransky (Observatory of Kyiv University, Ukraine) [Comet was near the Moon]
1998 Nov. 24.47 UT: m1=9.1, Dia.=3', DC=5 ... 20-cm L(x45) ... Michael Mattiazzo (Wallaroo, South Australia) [moonlight interference]
1998 Nov. 23.74 UT: m1=9.4, Dia.=3.7', DC=2/ ... 20-cm L (40x) ... Alexandr Baransky (Observatory of Kyiv University, Ukraine)
1998 Nov. 22.70 UT: m1=9.2, Dia.=4', DC=4 ... 20-cm L (40x) ... Alexandr Baransky (Observatory of Kyiv University, Ukraine)
1998 Nov. 21.81 UT: m1=9.5, Dia.=2', DC=2 ...  20-cm SCT (80x) ... Jose J. Chambo (Hoya Redonda, Valencia, Spain)
1998 Nov. 20.73 UT: m1=9.0:, Dia.=4', DC=3 ... 11-cm L (45x) ... Alexandr Baransky (Observatory of Kyiv University, Ukraine)
1998 Nov. 13.12 UT: m1=8.8, DC=3/ ... 20x80 B ... Charles S. Morris (Fillmore, CA) [Significantly fainter than C/1998 U5.]
1998 Nov. 12.98 UT: m1=8.5, Dia.=5', DC=4 ... 20x80 B ... J. Bortle (Stormville, NY)
1998 Nov. 12.74 UT: m1=9.0, Dia.=3.0', DC=D4 ... 25.4-cm L (65x) ... Maik Meyer (Frauenstein, Germany)
1998 Nov. 11.98 UT: m1=8.6, Dia.=5.5', DC= 5 ... 20x80 B ... J. Bortle (Stormville, NY) [41-cmL@70x gives m1=9.0, Dia.=2.3', DC=5-6, indications of a vague, faint tail to the ENE]
1998 Nov. 11.73 UT: m1=9.3, Dia.=3', DC=7 ... 15-cm R f/15 (141x) ... A. Diepvens (Balen, Belgium)
1998 Nov. 08.80 UT: m1=9.0, Dia.=4', DC=4 ... 21-cm L (60x) ... J. Carvajal (Madrid, Spain)
1998 Nov. 08.44 UT: m1=9.1, Dia.=2.5', DC=5 ... 20-cm L(x45) ... Michael Mattiazzo (Wallaroo, South Australia)
1998 Nov. 07.98 UT: m1=8.6, Dia.=6', DC=5 ... 20x80 B ... J. Bortle (Stormville, NY)
1998 Nov. 07.74 UT: m1=9.3, Dia.=2.9', DC=4 ... 25.4-cm L (65x) ... Maik Meyer (Frauenstein, Germany)
1998 Nov. 07.73 UT: m1=9.2, Dia.=2.3', DC=5 ... 13-cm R (35x) ... Wolfgang Vollmann (Payerbach, Austria)
1998 Nov. 07.23 UT: m1=9.2, Dia.=4.5', DC=6, Tail= 12' in PA: 65 deg. ... 25.6-cm L (42x) ... Nicolas Biver (Mokuleia, Oahu, HI)
1998 Nov. 06.80 UT: m1=8.8, Dia.=3', DC=4/ ... 10-cm R (27x) ... J. Carvajal (Madrid, Spain)
1998 Nov. 06.02 UT: m1=8.5, Dia.=5' ... 11x80 B ... Jose Guilherme de S. Aguiar (Campinas, S.P, Brazil)
1998 Nov. 05.98 UT: m1=8.8, Dia.=5.5', DC=5 ... 20x80 B ... J. Bortle (Stormville, NY) [With a 41-cmL@70x m1=9.2, Dia.=2.7', DC=5/6, Tail= 0.05 deg. in p.a. 055 degrees, coma strongly elongated in p.a. 055-235 with condensation offset sunward.]
1998 Nov. 02.97 UT: m1=9.4, Dia.=1', DC=4, Tail= no tail seen ... 15-cm L ... Gregorio Drayer (Caracas, Venezuela) [There was water vapor in the atmosphere reflecting the Moon's light.]
1998 Nov. 02.02 UT: m1=8.5, Dia.=3& ... 11x80 B ... Jose Guilherme de S. Aguiar (Campinas, S.P, Brazil)
1998 Nov. 01.98 UT: m1=9.3, Dia.=3', DC=4, Tail= 5' in PA: 75 deg. ... 15-cm L ... Gregorio Drayer (Caracas, Venezuela) [Diffuse nucleus, I noticed a change of position relative to background stars in 30 minutes ~1' in PA~120 deg. The Moon didn't let me continue because of light interference.]
1998 June 21.25 UT: m1=14.5 CCD, Dia.=1', DC=1 ... 45-cm CASS/ST6 ... Tom Johnston (Sommers-Bausch Observatory, Boulder, CO) [Deep image shows a hint of a fan tail]
1998 May  28.25 UT: m1=15.2 CCD, Dia.=30", DC=1 ... 31.25-cm L /ST7 ... Tom Johnston (Views Brothers Observatory, Luna Lake, AZ)

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