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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"

3757 results found.

  1. GRB 200227A: Enhanced Swift-XRT position
  2. LIGO/Virgo S200224ca : No significant candidates in TAROT - FRAM - GRANDMA observations
  3. GRB 200227A: Swift detection of a burst
  4. LIGO/Virgo S200225q: no counterpart candidate in SVOM/GWAC observations
  5. GRB 200224B: DDOTI/OAN optical observations report
  6. LIGO/Virgo S200224ca: No counterpart candidates in KAIT observations
  7. Fermi trigger No 604231129: Global MASTER-Net observations report
  8. LIGO/Virgo S200224ca: Subaru/Hyper Suprime-Cam follow-up observations
  9. Fermi trigger No 604213554: Global MASTER-Net observations report
  10. LIGO/Virgo S200219ac: no counterpart candidate in SVOM/GWAC-F30 observations
  11. LIGO/Virgo S200219ac: no counterpart candidate in SVOM/GWAC observations
  12. LIGO/Virgo S200219ac : No significant candidates in TAROT - FRAM - GRANDMA observations.
  13. LIGO/Virgo S200219ac: No counterpart candidates in KAIT observations
  14. Fermi trigger No 603949983: Global MASTER-Net observations report
  15. LIGO/Virgo S200219ac: No transient candidates in CALET observations
  16. Fermi trigger No 603849435: Global MASTER-Net observations report
  17. GRB 200219A: Swift-XRT refined Analysis
  18. LIGO/Virgo S200219ac: Global MASTER-Net observations report
  19. GRB 200216B: second epoch optical upper limit at Mondy observatory
  20. GRB 200216B: Mondy and AbAO optical upper limits
  21. LIGO/Virgo (S200213t/IceCube neutrino candidate: No counterpart candidates in the Swift-XRT Observations
  22. LIGO/Virgo S200213t: No EM counterparts found from continued GECKO observation of host galaxy candidates
  23. GRB 200216B: Swift-BAT refined analysis
  24. LIGO/Virgo S200213t : No significant candidates in FRAM - OAJ - TAROT - GRANDMA observations
  25. GRB 200216B - possible IR counterpart from VLT
  26. GRB 200216B: Enhanced Swift-XRT position
  27. GRB 200216B: Nanshan/NEXT early optical upper limit and possible host galaxy
  28. GRB 200216B: Swift detection of a burst
  29. LIGO/Virgo S200213t: No transient candidates in CALET observations
  30. LIGO/Virgo S200213t: No Counterparts from GECKO observation of host galaxy candidates in GW-neutrino detection overlap area
  31. LIGO/Virgo S200213t: No counterpart candidates in KAIT observations
  32. LIGO/Virgo S200208q : No significant candidates in TAROT - FRAM - GRANDMA observations
  33. LIGO/Virgo S200208q: no counterpart candidate in SVOM/C-GFT observations
  34. LIGO/Virgo trigger S200213t: Possible host galaxies
  35. ZTF20aajnksq: Upper limits from Konus-Wind observations
  36. LIGO/Virgo S200208q: No counterpart candidates in KAIT observations
  37. GRB 200211A: BALROG localization (Fermi Trigger 603098793 / GRB 200211310)
  38. GRB 200211A: Fermi GBM Final Real-time Localization
  39. LIGO/Virgo S200208q: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  40. Fermi trigger No 602817262: Global MASTER-Net observations report
  41. Swift GRB200205.81: Global MASTER-Net observations report
  42. Fermi trigger No 602455182: Global MASTER-Net observations report
  43. LIGO/Virgo S200128d: Upper limits from Konus-Wind observations
  44. GRB 200131A: ISON-Castelgrande optical observations
  45. GRB 200131A: VIRT optical transient detection
  46. LIGO/Virgo S200128d: no counterpart candidate in SVOM/GWAC observations
  47. LIGO/Virgo S200128d : No significant candidates in FRAM - TAROT - GRANDMA observations
  48. LIGO/Virgo S200128d: upper limits from AGILE/GRID observations
  49. LIGO/Virgo S200128d: No counterpart candidates in Fermi-LAT observations
  50. LIGO/Virgo S200128d: Upper limits from CALET observations
  51. LIGO/Virgo S200128d: No counterpart candidates in KAIT observations
  52. Fermi-LAT ANTARES coincidence: IceCube neutrino search
  53. GRB 200128B: AGILE/MCAL detection of a burst
  54. Fermi-LAT-ANTARES coincidence
  55. LIGO/Virgo S200128d : no neutrino counterpart candidate in ANTARES search
  56. LIGO/Virgo S200128d: Coverage and upper limits from MAXI/GSC observations
  57. GRB 200128A: Fermi GBM Final Real-time Localization
  58. LIGO/Virgo S200128d: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  59. LIGO/Virgo S200128d: Identification of a GW compact binary merger candidate
  60. LIGO/Virgo S200128d: Upper limits from IceCube neutrino searches
  61. LIGO/Virgo S200128d: Global MASTER-Net observations report
  62. Fermi trigger No 601729856: Global MASTER-Net observations report
  63. Fermi trigger No 601677816: Global MASTER-Net observations report
  64. Correction to GRB 200125A: Swift-XRT refined analysis
  65. LIGO/Virgo S200114f : No significant candidates in TAROT - FRAM - GRANDMA observations
  66. LIGO/Virgo S200115j: Zwicky Transient Facility search for optical counterparts to Swift X-ray sources
  67. Fermi trigger No 601363105: Global MASTER-Net observations report
  68. LIGO/Virgo S200115j : No significant candidates in TAROT - FRAM - GRANDMA observations
  69. GRB 200115A: Mondy optical observations and correction to GCN 26790
  70. LIGO/Virgo S200112r : No significant candidates in TAROT - FRAM - GRANDMA observations.
  71. Baksan Neutrino Observatory Alert 200116.22: Global MASTER-Net observations report
  72. IPN triangulation of GRB 200111A
  73. LIGO/Virgo S200115j: Candidates from the Zwicky Transient Facility
  74. LIGO/Virgo S200115j: INTEGRAL was inactive at the time of the event
  75. LIGO/Virgo S200112r: Upper limits from CALET observations
  76. LIGO/Virgo S200112r: upper limits from AGILE/GRID observations
  77. LIGO/Virgo S200105ae : No significant candidates in TAROT - FRAM - GRANDMA observations.
  78. Fermi trigger No 600227156: Global MASTER-Net observations report
  79. LIGO/Virgo S200105ae: Candidates from the Zwicky Transient Facility
  80. LIGO/Virgo S200105ae: Upper limits from CALET observations.
  81. GRB 200107B: Swift detection of a burst
  82. LIGO/Virgo S200105ae: Global MASTER-Net observations report
  83. Fermi trigger No 599954133: Global MASTER-Net observations report
  84. GRB 200105A: MAXI/GSC detection
  85. Fermi trigger No 599761015: Global MASTER-Net observations report
  86. IPN triangulation of GRB 200101A
  87. GRB 191228A: Early Optical Upper Limits from LCO
  88. IceCube Alert 200101.46: Global MASTER-Net observations report
  89. GRB 191228A: Mondy optical upper limit
  90. GRB 191228A: ePESSTO+ NTT optical upper limit
  91. GRB 191228A: UKIRT NIR upper limit
  92. LIGO/Virgo S191222n: No transient candidates in CALET observations
  93. Swift GRB191228.00: Global MASTER-Net observations report
  94. Swift GRB191227A: Global MASTER-Net OT detection
  95. Swift GRB191227.07: Global MASTER-Net observations report
  96. Swift GRB191226.02: Global MASTER-Net observations report
  97. LIGO/Virgo S191222n : No significant candidates in FRAM-TAROT-GRANDMA observations
  98. LIGO/Virgo S191222n: no counterpart candidate in SVOM/GWAC observations
  99. GRB 191221B: iTelescope optical observations
  100. LIGO/Virgo S191216ap: No significant candidates found in Pan-STARRS observations

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