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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"

5811 results found.

  1. EP250109a: Swift/UVOT non-detection
  2. EP250108a: Liverpool Telescope likely optical counterpart
  3. GRB 250108B: REM optical/NIR upper limits
  4. EP250109a: Global MASTER-Net observations report
  5. GRB 250101A: Terskol K-800 optical observations
  6. EP250109a: GOTO optical upper limits
  7. EP250109a: Swift/XRT non-detection
  8. EP250108a: Global MASTER-Net observations report
  9. EP250109a: EP-WXT detection of an X-ray transient
  10. LIGO/Virgo/KAGRA S250109bi: Identification of a GW compact binary merger candidate
  11. LIGO/Virgo/KAGRA S250109f: Identification of a GW compact binary merger candidate
  12. Fermi GRB 250107B: Global MASTER-Net observations report
  13. GRB 250103A: Fermi GBM Observation
  14. Fermi GRB 250102A: Global MASTER-Net observations report
  15. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  16. GRB 250101A: Swift detection of a burst with an optical counterpart
  17. GRB 240606B: 7DT Optical upper limits
  18. Fermi GRB 241228B: Global MASTER-Net observations report
  19. GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
  20. GRB 241228B: GOTO possible optical counterpart candidate
  21. GRB 241223A: GRBAlpha detection
  22. GRB 241212A: VZLUSAT-2 detection
  23. Fermi GRB 241226A: Global MASTER-Net observations report
  24. Fermi trigger No 756678579: Global MASTER-Net observations report
  25. IceCube Alert 241224.30: Global MASTER-Net observations report
  26. The EP-WXT trigger 01709129287 is likely a flaring star
  27. GRB 241217a/EP241217B: 1.6m Mephisto optical upper limits
  28. GRB 241217A / EP241217B: GRANDMA/T1MPicduMidi optical upperlimits
  29. GRB 241217A: refined SVOM/MXT data analysis. Long lasting X-ray emission.
  30. GRB 241217A / EP241217b: NOT optical upper limits
  31. GRB 241217a: Liverpool Telescope optical follow-up
  32. EP241217a: Global MASTER-Net observations report
  33. GRB 241209D: GRBAlpha detection
  34. GRB 241215A: Nanshan/HMT optical upper limit
  35. GRB 241212A: Fermi GBM detection
  36. EP241208a: NOT optical upper limits
  37. GRB 241212A: AstroSat CZTI detection
  38. GRB 241207A: TSHAO Zeiss-1000 optical observations
  39. GRB 241212A: Fermi GBM Final Real-time Localization
  40. GRB 241209B: GRBAlpha detection
  41. GRB 241209C: Fermi GBM Observation
  42. LIGO/Virgo/KAGRA S241210fu: Identification of a GW compact binary merger candidate
  43. GRB 241209D: AstroSat CZTI detection
  44. EP241208a: Global MASTER-Net observations report
  45. EP241208a: EP-FXT follow-up observations
  46. Fermi trigger No 755485387: Global MASTER-Net observations report
  47. GRB 241209D: Fermi GBM Observation
  48. GRB 241209A: VLT/HAWK-I near-IR counterpart candidate
  49. GRB 241209D: COLIBRÍ detection of the afterglow
  50. Fermi GRB 241209D: Global MASTER-Net observations report
  51. GRB 241209A: Fermi GBM Observation
  52. GRB 241209B: BOOTES-5 optical upper limit
  53. Swift GRB 241209D: Global MASTER-Net observations report
  54. Fermi GRB 241209C: Global MASTER-Net observations report
  55. Fermi GRB 241209E: Global MASTER-Net observations report
  56. LIGO/Virgo/KAGRA S241102br: continued GRAWITA observations and detection of an optical transient (AT2024adip)
  57. GRB 241209A: REM optical/NIR observations
  58. GRB 241209C: AstroSat CZTI detection
  59. Fermi GRB 241209A: Global MASTER-Net observations report
  60. GRB 241209A: GOTO optical upper limits
  61. GRB 241209B: SVOM/ECLAIRs and GRM detection of a long burst
  62. Swift GRB241209.23: Global MASTER-Net observations report
  63. Fermi GRB 241207B: Global MASTER-Net observations report
  64. GRB 241206A: DDOTI Upper Limit on the Afterglow
  65. GRB 241207C: MASTER optical observations
  66. Fermi trigger No 755225799: Global MASTER-Net observations report
  67. Fermi GRB 241207A: Global MASTER-Net observations report
  68. Fermi GRB 241206A: Global MASTER-Net observations report
  69. Fermi GRB 241204A: Global MASTER-Net observations report
  70. EP241201a: Global MASTER-Net observations report
  71. Fermi GRB 241201A: Global MASTER-Net observations report
  72. LIGO/Virgo S241127aj: GRANDMA/FRAM-CTA-N Observations
  73. GRB 241127A: Swift detection of a burst with an optical counterpart
  74. LIGO/Virgo/KAGRA S241127aj: NED Galaxies in the Localization Volume
  75. LIGO/Virgo/KAGRA S241125n: SAGUARO follow-up observations with the MMT
  76. LIGO/Virgo/KAGRA S241109bn: Upper limits from a two-week IceCube neutrino search
  77. IPN triangulation of GRB 241117A
  78. EP trigger ID 01709065118: Keck/LRIS spectroscopic observations
  79. Fermi GRB 241118A: Global MASTER-Net observations report
  80. Fermi GRB 241117A: Global MASTER-Net observations report
  81. LIGO/Virgo/KAGRA S241116cq: Identification of a GW compact binary merger candidate
  82. EP241113a: No Detection in Fermi-GBM Observations
  83. LIGO/Virgo/KAGRA S241114bi: Coverage and upper limits from MAXI/GSC observations
  84. EP241113a: Global MASTER-Net observations report
  85. EP241113b: Global MASTER-Net observations report
  86. EP241113a: EP on-board trigger and autonomous follow-up observation
  87. GRB 241113A: LCO optical observations
  88. GRB241113A: LCOGT (40-cm) optical counterpart detection
  89. Fermi trigger No 753166198: Global MASTER-Net observations report
  90. GRB 241112B: AbAO optical upper limit
  91. Fermi GRB 241112A: Global MASTER-Net observations report
  92. GRB 241112B: Swift-XRT afterglow detection
  93. GRB 241112B: SVOM/VT afterglow detection
  94. EP241107a: EP-FXT follow-up observations
  95. GRB 241025C: VZLUSAT-2 detection
  96. LIGO/Virgo/KAGRA S241110bk: 1 counterpart neutrino candidate event from an IceCube neutrino search
  97. LIGO/Virgo/KAGRA S241110br: Identification of a GW compact binary merger candidate
  98. LIGO/Virgo/KAGRA S241109bn: Upper limits from EP-WXT observations
  99. Fermi trigger No 752878030: Global MASTER-Net observations report
  100. LIGO/Virgo/KAGRA S241109bn: Coverage and upper limits from MAXI/GSC observations

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