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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

3386 results found.

  1. GRB 200401A: Fermi GBM Final Real-time Localization
  2. GRB 200325B: Mondy continued observations
  3. GRB 200325B: Mondy continued observations
  4. IPN triangulation of GRB 200327A (short)
  5. Fermi trigger No 606918292: Global MASTER-Net observations report
  6. LIGO/Virgo S200316bj: no counterpart candidate in SVOM/GWAC-F30 observations
  7. LIGO/Virgo S200316bj : No significant candidates in TAROT - FRAM - GRANDMA observations.
  8. LIGO/Virgo S200316bj: Upper limits from CALET observations
  9. LIGO/Virgo S200316bj: No Counterparts in DDOTI/OAN Optical Observations
  10. IPN triangulation of GRB 200311A
  11. GRB 200310A: MAXI/GSC detection
  12. GRB 200306C: BOOTES-1 detection of the optical afterglow
  13. LIGO/Virgo S200302c : No significant candidates in FRAM - TAROT - GRANDMA observations.
  14. GRB 200228A: AstroSat CZTI detection
  15. LIGO/Virgo S200302c: No transient candidates in CALET observations
  16. Fermi trigger No 604895668: Global MASTER-Net observations report
  17. LIGO/Virgo S200302c: No counterpart candidates in KAIT observations
  18. LIGO/Virgo S200302c: Coverage and upper limits from MAXI/GSC observations
  19. GRB 200228B: Mondy, TSHAO, AbAO and CrAO optical observations, afterglow candidate
  20. LIGO/Virgo S200225q : No significant candidates in TAROT - FRAM - GRANDMA observations.
  21. Swift GRB 200228B: Global MASTER-Net observations report
  22. GRB 200228B: Fermi GBM observation
  23. IceCube-200227A: Upper limits from a search for additional neutrino events in IceCube
  24. GRB 200228A: Fermi GBM observation
  25. LIGO/Virgo S200213t: No significant EM counterparts identified from continued GECKO observation of host galaxy candidates
  26. GRB 200228B: Fermi GBM Final Real-time Localization
  27. Fermi trigger No 604565918: Global MASTER-Net observations report
  28. GRB 200228A: BALROG localization (Fermi Trigger 604565918 / GRB 200228291)
  29. GRB 200228A: Fermi GBM Final Real-time Localization
  30. GRB 200227A: Enhanced Swift-XRT position
  31. LIGO/Virgo S200224ca : No significant candidates in TAROT - FRAM - GRANDMA observations
  32. GRB 200227A: Swift detection of a burst
  33. LIGO/Virgo S200225q: no counterpart candidate in SVOM/GWAC observations
  34. GRB 200224B: DDOTI/OAN optical observations report
  35. LIGO/Virgo S200224ca: No counterpart candidates in KAIT observations
  36. Fermi trigger No 604231129: Global MASTER-Net observations report
  37. LIGO/Virgo S200224ca: Subaru/Hyper Suprime-Cam follow-up observations
  38. Fermi trigger No 604213554: Global MASTER-Net observations report
  39. LIGO/Virgo S200219ac: no counterpart candidate in SVOM/GWAC-F30 observations
  40. LIGO/Virgo S200219ac: no counterpart candidate in SVOM/GWAC observations
  41. LIGO/Virgo S200219ac : No significant candidates in TAROT - FRAM - GRANDMA observations.
  42. LIGO/Virgo S200219ac: No counterpart candidates in KAIT observations
  43. Fermi trigger No 603949983: Global MASTER-Net observations report
  44. LIGO/Virgo S200219ac: No transient candidates in CALET observations
  45. Fermi trigger No 603849435: Global MASTER-Net observations report
  46. GRB 200219A: Swift-XRT refined Analysis
  47. LIGO/Virgo S200219ac: Global MASTER-Net observations report
  48. GRB 200216B: second epoch optical upper limit at Mondy observatory
  49. GRB 200216B: Mondy and AbAO optical upper limits
  50. LIGO/Virgo (S200213t/IceCube neutrino candidate: No counterpart candidates in the Swift-XRT Observations
  51. LIGO/Virgo S200213t: No EM counterparts found from continued GECKO observation of host galaxy candidates
  52. GRB 200216B: Swift-BAT refined analysis
  53. LIGO/Virgo S200213t : No significant candidates in FRAM - OAJ - TAROT - GRANDMA observations
  54. GRB 200216B - possible IR counterpart from VLT
  55. GRB 200216B: Enhanced Swift-XRT position
  56. GRB 200216B: Nanshan/NEXT early optical upper limit and possible host galaxy
  57. GRB 200216B: Swift detection of a burst
  58. LIGO/Virgo S200213t: No transient candidates in CALET observations
  59. LIGO/Virgo S200213t: No Counterparts from GECKO observation of host galaxy candidates in GW-neutrino detection overlap area
  60. LIGO/Virgo S200213t: No counterpart candidates in KAIT observations
  61. LIGO/Virgo S200208q : No significant candidates in TAROT - FRAM - GRANDMA observations
  62. LIGO/Virgo S200208q: no counterpart candidate in SVOM/C-GFT observations
  63. LIGO/Virgo trigger S200213t: Possible host galaxies
  64. ZTF20aajnksq: Upper limits from Konus-Wind observations
  65. LIGO/Virgo S200208q: No counterpart candidates in KAIT observations
  66. GRB 200211A: BALROG localization (Fermi Trigger 603098793 / GRB 200211310)
  67. GRB 200211A: Fermi GBM Final Real-time Localization
  68. LIGO/Virgo S200208q: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  69. Fermi trigger No 602817262: Global MASTER-Net observations report
  70. Swift GRB200205.81: Global MASTER-Net observations report
  71. Fermi trigger No 602455182: Global MASTER-Net observations report
  72. LIGO/Virgo S200128d: Upper limits from Konus-Wind observations
  73. GRB 200131A: ISON-Castelgrande optical observations
  74. GRB 200131A: VIRT optical transient detection
  75. LIGO/Virgo S200128d: no counterpart candidate in SVOM/GWAC observations
  76. LIGO/Virgo S200128d : No significant candidates in FRAM - TAROT - GRANDMA observations
  77. LIGO/Virgo S200128d: upper limits from AGILE/GRID observations
  78. LIGO/Virgo S200128d: No counterpart candidates in Fermi-LAT observations
  79. LIGO/Virgo S200128d: Upper limits from CALET observations
  80. LIGO/Virgo S200128d: No counterpart candidates in KAIT observations
  81. Fermi-LAT ANTARES coincidence: IceCube neutrino search
  82. GRB 200128B: AGILE/MCAL detection of a burst
  83. Fermi-LAT-ANTARES coincidence
  84. LIGO/Virgo S200128d : no neutrino counterpart candidate in ANTARES search
  85. LIGO/Virgo S200128d: Coverage and upper limits from MAXI/GSC observations
  86. GRB 200128A: Fermi GBM Final Real-time Localization
  87. LIGO/Virgo S200128d: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  88. LIGO/Virgo S200128d: Identification of a GW compact binary merger candidate
  89. LIGO/Virgo S200128d: Upper limits from IceCube neutrino searches
  90. LIGO/Virgo S200128d: Global MASTER-Net observations report
  91. Fermi trigger No 601729856: Global MASTER-Net observations report
  92. Fermi trigger No 601677816: Global MASTER-Net observations report
  93. Correction to GRB 200125A: Swift-XRT refined analysis
  94. LIGO/Virgo S200114f : No significant candidates in TAROT - FRAM - GRANDMA observations
  95. LIGO/Virgo S200115j: Zwicky Transient Facility search for optical counterparts to Swift X-ray sources
  96. Fermi trigger No 601363105: Global MASTER-Net observations report
  97. LIGO/Virgo S200115j : No significant candidates in TAROT - FRAM - GRANDMA observations
  98. GRB 200115A: Mondy optical observations and correction to GCN 26790
  99. LIGO/Virgo S200112r : No significant candidates in TAROT - FRAM - GRANDMA observations.
  100. Baksan Neutrino Observatory Alert 200116.22: Global MASTER-Net observations report

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