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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"

3798 results found.

  1. LIGO/Virgo/KAGRA S230520ae: Upper limits from IceCube neutrino search
  2. LIGO/Virgo/KAGRA S230518h: GECKO tiling observations with KMTNet
  3. GRB 230520A: MAXI/GSC detection
  4. LIGO/Virgo/KAGRA S230518h: Coverage and upper limits from MAXI/GSC observations
  5. LIGO/Virgo S230518h: Global MASTER-Net observations report
  6. LIGO/Virgo S230518h: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  7. GRB 230510B: Fermi GBM detection
  8. GRB 230510B: AstroSat CZTI detection
  9. GRB 230510B: CALET Gamma-Ray Burst Monitor detection
  10. GRB 230510B: MAXI/GSC detection
  11. GRB 230506C: TSHAO possible afterglow candidate
  12. GRB 230420A: Swift-BAT refined analysis
  13. GRB 230409B: 3.6m DOT near-infrared detection, afterglow confirmation
  14. GRB 230409B: Mondy optical upper limit
  15. Fermi trigger No 702745263: Global MASTER-Net observations report
  16. MAXI GRB230408.82: Global MASTER-Net observations report
  17. GRB 230409B: Swift detection of a burst
  18. Fermi trigger No 701883729: Global MASTER-Net observations report
  19. GRB 230328B: Swift-BAT refined analysis
  20. GRB 230328B: Nanshan/NEXT optical upper limit
  21. Fermi GRB 230328A: Global MASTER-Net observations report
  22. Fermi trigger No 701321709: Global MASTER-Net observations report
  23. Konus-Wind detection of GRB 230309A
  24. GRB 230322A: Fermi GBM Final Real-time Localization
  25. Fermi GRB 230313A: Global MASTER-Net observations report
  26. GRB 230307A: soft X-ray detection with LEIA
  27. Further improved IPN localization for GRB 230307A
  28. GRB 230307A: MAXI/GSC upper limit
  29. Fermi GRB 230308A: Global MASTER-Net observations report
  30. Fermi trigger No 699294715: Global MASTER-Net observations report
  31. Fermi trigger No 699311646: Global MASTER-Net observations report
  32. GRB 230220A: Correction to GCN 33352
  33. Fermi GRB 230220B: Global MASTER-Net observations report
  34. GRB 230220A: MAXI/GSC detection
  35. IceCube-230217A: BOOTES-4/MET Optical Observations
  36. IPN triangulation of GRB 230209B
  37. GRB 230204B: CALET Gamma-Ray Burst Monitor detection
  38. GRB 230204B: ATCA radio detection
  39. Fermi trigger No 697926015: Global MASTER-Net observations report
  40. Fermi trigger No 697904388: Global MASTER-Net observations report
  41. GRB 230204B: MASTER early OT detection
  42. GRB 230204B: Swift/UVOT Upper Limits
  43. GRB 230204B: Fermi GBM detection
  44. GRB 230204B: Swift-XRT afterglow detection
  45. GRB 230204B: 3.6m DOT optical observation
  46. GRB 230204B: ATLAS detection of the optical afterglow and a projected location in a nearby galaxy group
  47. GRB 230204B: Swift ToO observations
  48. GRB 230204B: Detection by GRBAlpha
  49. GRB 230204B: AGILE detection
  50. GRB 230204B: GIT discovery of the likely optical afterglow
  51. GRB 230204B: AstroSat CZTI detection
  52. GRB 230204B: Swift/BAT-GUANO detection outside the coded FOV
  53. GRB 230204B: MAXI/GSC detection
  54. GRB 230204A/Swift J1552.8-5055: LCOGT Optical Counterpart Candidate
  55. GRB 230204A: Swift detection of a possible burst (or possible transient Swift J1552.8-5055)
  56. Fermi trigger No 697098930: Global MASTER-Net observations report
  57. GRB 221216A: Swift-BAT refined analysis
  58. Fermi GRB 230201A: Global MASTER-Net observations report
  59. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-221229A
  60. GRB 230111A: Fermi GBM Observation
  61. Fermi GRB 230112A: Global MASTER-Net observations report
  62. GRB 230111A: MAXI/GSC detection
  63. Subject: IceCube-Cascade 221229A: Upper limits from a search for additional neutrino events in IceCube
  64. Fermi GRB 221226A: Global MASTER-Net observations report
  65. Fermi GRB 221221A: Global MASTER-Net observations report
  66. IceCube-221216A: No Candidate Counterparts from the Zwicky Transient Facility
  67. Integral GRB221218.34: Global MASTER-Net observations report
  68. Fermi trigger No 692713692: Global MASTER-Net observations report
  69. Swift Trigger 1144538 is not a GRB
  70. Konus-Wind detection of a burst from SGR 1935+2154 on 2022 December 13
  71. Fermi GRB 221211A: Global MASTER-Net observations report
  72. IceCube Alert 221210.36: Global MASTER-Net observations report
  73. IceCube Alert 221124.66: Global MASTER-Net observations report
  74. LAT GRB221119.63: Global MASTER-Net observations report
  75. GRB 221028A: CrAO/ZTSh optical upper limit
  76. GRB 221028B: MAXI/GSC detection
  77. Konus-Wind detection of GRB 221017A
  78. Swift GRB 221027B: Global MASTER-Net observations report
  79. GRB 221022B: Detection by GRBAlpha
  80. GRB 221017A: CALET Gamma-Ray Burst Monitor detection
  81. GRB 221017A: Swift-XRT observations
  82. GRB 221017A: Swift ToO observations
  83. AGILE detection of short X-ray flaring activity contemporary to SGR J1935+2154 reported bursts
  84. IPN triangulation of GRB 221017A (long)
  85. MAXI GRB221017.24: Global MASTER-Net observations report
  86. GRB 221017A: MAXI/GSC detection
  87. MAXI/GSC refined analysis of the bright X-ray afterglow of GRB 221009A/Swift J1913.1+1946
  88. MAXI GRB 221006A: Redshifts of the possible host galaxies
  89. Fermi trigger No 687340841: Global MASTER-Net observations report
  90. GRB 221006A: Swift-XRT afterglow detection
  91. Fermi trigger No 687281393: Global MASTER-Net observations report
  92. Afterglow limits of GRB 221006A from OHP
  93. GRB 221009A: NICER follow-up observations
  94. Fermi trigger No 687190301: Global MASTER-Net observations report
  95. GRB 221009A: 10.4m GTC spectroscopic redshift confirmation
  96. GRB 221009A: Upper limits from HAWC 8 hours after trigger
  97. GRB 221006A: Swift ToO observations
  98. GRB 221006A: CALET Gamma-Ray Burst Monitor detection
  99. GRB 221009A (Swift J1913.1+1946): Burke-Gaffney Observatory optical observations
  100. GRB 221009A BOOTES-2/TELMA and OSN optical detections

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