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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"

3758 results found.

  1. GRB 200228A: Fermi GBM Final Real-time Localization
  2. GRB 200227A: Enhanced Swift-XRT position
  3. LIGO/Virgo S200224ca : No significant candidates in TAROT - FRAM - GRANDMA observations
  4. GRB 200227A: Swift detection of a burst
  5. LIGO/Virgo S200225q: no counterpart candidate in SVOM/GWAC observations
  6. GRB 200224B: DDOTI/OAN optical observations report
  7. LIGO/Virgo S200224ca: No counterpart candidates in KAIT observations
  8. Fermi trigger No 604231129: Global MASTER-Net observations report
  9. LIGO/Virgo S200224ca: Subaru/Hyper Suprime-Cam follow-up observations
  10. Fermi trigger No 604213554: Global MASTER-Net observations report
  11. LIGO/Virgo S200219ac: no counterpart candidate in SVOM/GWAC-F30 observations
  12. LIGO/Virgo S200219ac: no counterpart candidate in SVOM/GWAC observations
  13. LIGO/Virgo S200219ac : No significant candidates in TAROT - FRAM - GRANDMA observations.
  14. LIGO/Virgo S200219ac: No counterpart candidates in KAIT observations
  15. Fermi trigger No 603949983: Global MASTER-Net observations report
  16. LIGO/Virgo S200219ac: No transient candidates in CALET observations
  17. Fermi trigger No 603849435: Global MASTER-Net observations report
  18. GRB 200219A: Swift-XRT refined Analysis
  19. LIGO/Virgo S200219ac: Global MASTER-Net observations report
  20. GRB 200216B: second epoch optical upper limit at Mondy observatory
  21. GRB 200216B: Mondy and AbAO optical upper limits
  22. LIGO/Virgo (S200213t/IceCube neutrino candidate: No counterpart candidates in the Swift-XRT Observations
  23. LIGO/Virgo S200213t: No EM counterparts found from continued GECKO observation of host galaxy candidates
  24. GRB 200216B: Swift-BAT refined analysis
  25. LIGO/Virgo S200213t : No significant candidates in FRAM - OAJ - TAROT - GRANDMA observations
  26. GRB 200216B - possible IR counterpart from VLT
  27. GRB 200216B: Enhanced Swift-XRT position
  28. GRB 200216B: Nanshan/NEXT early optical upper limit and possible host galaxy
  29. GRB 200216B: Swift detection of a burst
  30. LIGO/Virgo S200213t: No transient candidates in CALET observations
  31. LIGO/Virgo S200213t: No Counterparts from GECKO observation of host galaxy candidates in GW-neutrino detection overlap area
  32. LIGO/Virgo S200213t: No counterpart candidates in KAIT observations
  33. LIGO/Virgo S200208q : No significant candidates in TAROT - FRAM - GRANDMA observations
  34. LIGO/Virgo S200208q: no counterpart candidate in SVOM/C-GFT observations
  35. LIGO/Virgo trigger S200213t: Possible host galaxies
  36. ZTF20aajnksq: Upper limits from Konus-Wind observations
  37. LIGO/Virgo S200208q: No counterpart candidates in KAIT observations
  38. GRB 200211A: BALROG localization (Fermi Trigger 603098793 / GRB 200211310)
  39. GRB 200211A: Fermi GBM Final Real-time Localization
  40. LIGO/Virgo S200208q: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  41. Fermi trigger No 602817262: Global MASTER-Net observations report
  42. Swift GRB200205.81: Global MASTER-Net observations report
  43. Fermi trigger No 602455182: Global MASTER-Net observations report
  44. LIGO/Virgo S200128d: Upper limits from Konus-Wind observations
  45. GRB 200131A: ISON-Castelgrande optical observations
  46. GRB 200131A: VIRT optical transient detection
  47. LIGO/Virgo S200128d: no counterpart candidate in SVOM/GWAC observations
  48. LIGO/Virgo S200128d : No significant candidates in FRAM - TAROT - GRANDMA observations
  49. LIGO/Virgo S200128d: upper limits from AGILE/GRID observations
  50. LIGO/Virgo S200128d: No counterpart candidates in Fermi-LAT observations
  51. LIGO/Virgo S200128d: Upper limits from CALET observations
  52. LIGO/Virgo S200128d: No counterpart candidates in KAIT observations
  53. Fermi-LAT ANTARES coincidence: IceCube neutrino search
  54. GRB 200128B: AGILE/MCAL detection of a burst
  55. Fermi-LAT-ANTARES coincidence
  56. LIGO/Virgo S200128d : no neutrino counterpart candidate in ANTARES search
  57. LIGO/Virgo S200128d: Coverage and upper limits from MAXI/GSC observations
  58. GRB 200128A: Fermi GBM Final Real-time Localization
  59. LIGO/Virgo S200128d: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  60. LIGO/Virgo S200128d: Identification of a GW compact binary merger candidate
  61. LIGO/Virgo S200128d: Upper limits from IceCube neutrino searches
  62. LIGO/Virgo S200128d: Global MASTER-Net observations report
  63. Fermi trigger No 601729856: Global MASTER-Net observations report
  64. Fermi trigger No 601677816: Global MASTER-Net observations report
  65. Correction to GRB 200125A: Swift-XRT refined analysis
  66. LIGO/Virgo S200114f : No significant candidates in TAROT - FRAM - GRANDMA observations
  67. LIGO/Virgo S200115j: Zwicky Transient Facility search for optical counterparts to Swift X-ray sources
  68. Fermi trigger No 601363105: Global MASTER-Net observations report
  69. LIGO/Virgo S200115j : No significant candidates in TAROT - FRAM - GRANDMA observations
  70. GRB 200115A: Mondy optical observations and correction to GCN 26790
  71. LIGO/Virgo S200112r : No significant candidates in TAROT - FRAM - GRANDMA observations.
  72. Baksan Neutrino Observatory Alert 200116.22: Global MASTER-Net observations report
  73. IPN triangulation of GRB 200111A
  74. LIGO/Virgo S200115j: Candidates from the Zwicky Transient Facility
  75. LIGO/Virgo S200115j: INTEGRAL was inactive at the time of the event
  76. LIGO/Virgo S200112r: Upper limits from CALET observations
  77. LIGO/Virgo S200112r: upper limits from AGILE/GRID observations
  78. LIGO/Virgo S200105ae : No significant candidates in TAROT - FRAM - GRANDMA observations.
  79. Fermi trigger No 600227156: Global MASTER-Net observations report
  80. LIGO/Virgo S200105ae: Candidates from the Zwicky Transient Facility
  81. LIGO/Virgo S200105ae: Upper limits from CALET observations.
  82. GRB 200107B: Swift detection of a burst
  83. LIGO/Virgo S200105ae: Global MASTER-Net observations report
  84. Fermi trigger No 599954133: Global MASTER-Net observations report
  85. GRB 200105A: MAXI/GSC detection
  86. Fermi trigger No 599761015: Global MASTER-Net observations report
  87. IPN triangulation of GRB 200101A
  88. GRB 191228A: Early Optical Upper Limits from LCO
  89. IceCube Alert 200101.46: Global MASTER-Net observations report
  90. GRB 191228A: Mondy optical upper limit
  91. GRB 191228A: ePESSTO+ NTT optical upper limit
  92. GRB 191228A: UKIRT NIR upper limit
  93. LIGO/Virgo S191222n: No transient candidates in CALET observations
  94. Swift GRB191228.00: Global MASTER-Net observations report
  95. Swift GRB191227A: Global MASTER-Net OT detection
  96. Swift GRB191227.07: Global MASTER-Net observations report
  97. Swift GRB191226.02: Global MASTER-Net observations report
  98. LIGO/Virgo S191222n : No significant candidates in FRAM-TAROT-GRANDMA observations
  99. LIGO/Virgo S191222n: no counterpart candidate in SVOM/GWAC observations
  100. GRB 191221B: iTelescope optical observations

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