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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"

28725 results found.

  1. GRB 210123A: Fermi GBM Final Localization
  2. IPN triangulation of GRB 210121A
  3. GRB 210121A: GECAM detection
  4. GRB 210120A : 1.3m DFOT optical observations
  5. ZTF21aaeyldq: GROND and CAHA jet break confirmation
  6. ZTF20aaeyldq: VLA radio detection
  7. GRB 210116A: AstroSat CZTI detection
  8. GRB 210120A(MASTER OT J105242.66+152355.0 / AT2021axc): Mondy optical observations
  9. GRB 210120A: MASTER OT (possibly) discovery
  10. GECAM In-Flight Trigger of GRB 210120A
  11. GRB 210104A: 3.6m DOT optical upper limit
  12. Fermi GRB 210120A: Global MASTER-Net observations report
  13. GRB 210112A: 3.6m DOT optical detection
  14. GRB 210119A (Swift J1851.2-6148): Swift-BAT refined analysis
  15. GECAM detection of a short GRB 210119A or a new SGR candidate Swift J1851.2-6148
  16. ZTF21aaeyldq: GROND observations
  17. GRB 210119A: Insight-HXMT/HE detection
  18. GRB 210119A: Fermi GBM observation
  19. ZTF21aaeyldq: LBT near-infrared observations
  20. GRB 210112A: Insight-HXMT/HE detection
  21. Short Fermi GRB 210119A or new SGR Swift J1851.2-6148: Possible MASTER Short OT detection
  22. Fermi GRB 210119A: Global MASTER-Net observations report
  23. ZTF21aaeyldq CAHA 2.2m detection and power-law decay
  24. GRB 200613A: Host galaxy redshift from OSIRIS/GTC
  25. GRB 210112A: Deep CAHA 2.2m detection
  26. GRB 210104A: Late-time CAHA 2.2m detection
  27. ZTF21aaeyldq: KPED observations
  28. Konus-Wind detection of GRB 210112A
  29. Correction to GCN 29288: NuEm-210111A: No counterpart candidates in INTEGRAL SPI-ACS observation
  30. ZTF21aaeyldq (AT2021any): Detection of X-ray Emission with Swift/XRT
  31. ZTF21aaeyldq: 2.2m CAHA BVRI optical observations
  32. GRB 201221D: near-infrared observation with LBT
  33. ZTF21aaeyldq: NOT optical observations
  34. ZTF21aaeyldq: Lowell Discovery Telescope observations
  35. ZTF21aaeyldq: observations with the 3.6m Devasthal Optical Telescope
  36. ZTF21aaeyldq: GTC Redshift and GRB afterglow nature confirmation
  37. GRB 201015A: evidence of supernova in LBT spectra
  38. GRB 210104A: JCMT SCUBA-2 sub-mm observations
  39. GRB 210112A: Swift/UVOT Detection
  40. GRB 210112A: Mondy optical observations
  41. GRB 210112A: 1.3m DFOT Optical upper limit
  42. GRB 210112A: OSN second epoch, decay
  43. GRB 210104A: AstroSat CZTI detection
  44. NuEm-210111A: MAXI/GSC upper limit
  45. GRB 210112A: Swift-BAT refined analysis
  46. GRB 210112A: OSN Reddened Afterglow Detection
  47. GRB 210112A: Swift-XRT refined Analysis
  48. GRB 210112A: Kitab a optical upper limit
  49. GRB 210104A: AROMA-N Optical Afterglow Detection
  50. NuEm-210111A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  51. GRB 210104A: Mondy optical observations, light curve
  52. GRB 210104A: Assy continued optical observations, correction to GCN circ. 29265
  53. GRB 201227A: continued Chilescope confirmation of variability of possible optical counterpart, redshift estimating
  54. Correction to GCN 29278: GRB 201216C XRT refined analysis
  55. GRB 201216C: Swift-XRT refined Analysis
  56. GRB 210104A: SAO RAS optical observations
  57. GRB 201227A: ASIM observation
  58. GRB 210104A: GMG observations
  59. GRB210104A: VIRT optical transient detection.
  60. GRB 210104A: SARA-KP 0.9m Optical Afterglow Detection
  61. GRB 210102B: further Swift-XRT observations
  62. GRB 210102B: Assy optical afterglow identification
  63. GRB 210104A: iTelescope optical upper limit
  64. GRB 210104A: CALET Gamma-Ray Burst Monitor detection
  65. GRB 210104B: Swift-BAT refined analysis
  66. GRB 210104A: Assy continued optical observations
  67. Fermi GRB 210105A: Global MASTER-Net observations report
  68. GW170817: HST observations at 3.4 years from merger
  69. GRB 210104A: early ATLAS detections of the bright afterglow
  70. GRB 210104A: Swift-XRT refined Analysis
  71. GRB 210104B: Swift/UVOT Upper Limits
  72. Konus-Wind detection of GRB 210104A
  73. GRB 210104A: 1.3m DFOT Optical Afterglow Detection
  74. GRB 210104B: Swift-XRT refined Analysis
  75. GRB 210104B: Assy optical upper limit
  76. GRB 210104A: DOAO optical afterglow observations
  77. GRB 210104A: Nanshan/NEXT optical powerlaw decay
  78. GRB 210104A: Swift-BAT refined analysis
  79. GRB 210104B: Nanshan/NEXT optical upper limit
  80. GRB 210104A: MASTER OT rebrightening detection
  81. GRB 210104A: Swift/UVOT Detection
  82. GRB 210104A: Fermi GBM detection
  83. GRB 210102B: Tiled Swift observations
  84. GRB 210104A: MITSuME Ishigaki optical observation
  85. GRB 210102B: Assy optical observations
  86. Fermi GRB 210104A: Global MASTER-Net observations report
  87. GRB 210104A: Assy optical observations
  88. GRB 210104A: MITSuME Akeno optical observation
  89. GRB 210104A: GWAC-F60A optical afterglow observations
  90. GRB 210102C: Swift-BAT refined analysis
  91. GRB 210102B: Swift-XRT observations
  92. Fermi GRB 210102C: Global MASTER-Net observations report
  93. GRB 210102C: Fermi GBM detection
  94. Swift GRB 210102C: Global MASTER-Net observations report
  95. GRB 210102B: Tiled Swift observations
  96. Fermi GRB 210101A: Global MASTER-Net observations report
  97. Swift Trigger 1015615 is not a GRB
  98. GRB 201229A: Swift/UVOT Detection
  99. GRB 201216C: TSHAO, Terskol, Mondy optical upper limits
  100. GRB 201227A: Chilescope optical observations, possible optical counterpart

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