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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"
  1. Fermi trigger No 633879387: Global MASTER-Net observations report
  2. GECAM observations of SGR 1935+2154
  3. GRB 210129A: Insight-HXMT/HE detection
  4. Continued Chandra observations of GW170817 at ~3.3 years since merger
  5. Fermi GBM Observations of SGR J1935+2154
  6. Konus-Wind detection of two bright bursts from SGR 1935+2154
  7. GRB 140330A: Swift-XRT refined Analysis
  8. GRB 140320B: Swift-XRT refined Analysis
  9. GRB 140402A: Swift-XRT refined Analysis
  10. GRB 140104B: Swift-XRT refined Analysis
  11. GRB 210126A: AstroSat CZTI detection
  12. GRB 210124B: AstroSat CZTI detection
  13. GRB 210123A: AstroSat CZTI detection
  14. IPN triangulation of a bright burst from SGR 1935+2154
  15. ZTF21aaeyldq: Observations with the 3.6m DOT
  16. GECAM detection of a short burst probably from SGR 1935+2154
  17. GRB 210127A: Fermi GBM Final Real-time Localization
  18. GRB 210120A: Fermi GBM detection
  19. Fermi trigger No 633348010: Global MASTER-Net observations report
  20. HAWC Transient event on 2021/01/25
  21. Konus-Wind detection of GRB 210121A
  22. Konus-Wind detection of GRB 210124B
  23. GRB 210126A: GECAM detection
  24. IPN triangulation of GRB 210124B (short)
  25. GRB 210126A: BALROG localization (Fermi Trigger / GRB 210126417)
  26. GRB 210124B: Insight-HXMT/HE detection
  27. Fermi trigger No 633257525: Global MASTER-Net observations report
  28. GRB 210123A: Fermi GBM Final Localization
  29. GECAM detection of a burst possibly from the X-ray burster 4U 0614+09 or GRB 210124A
  30. GRB 210123A: Insight-HXMT/HE detection
  31. IPN triangulation of GRB 210121A
  32. GRB 210121A: GECAM detection
  33. GRB 210121A: Insight-HXMT/HE detection
  34. GRB 210120A : 1.3m DFOT optical observations
  35. ZTF21aaeyldq: GROND and CAHA jet break confirmation
  36. ZTF20aaeyldq: VLA radio detection
  37. GRB 210116A: AstroSat CZTI detection
  38. GRB 210120A(MASTER OT J105242.66+152355.0 / AT2021axc): Mondy optical observations
  39. GRB 210116: AstroSat LAXPC detection
  40. GRB 210120A: MASTER OT (possibly) discovery
  41. GECAM In-Flight Trigger of GRB 210120A
  42. GRB 210104A: 3.6m DOT optical upper limit
  43. Fermi GRB 210120A: Global MASTER-Net observations report
  44. GRB 210120A: BALROG localization (Fermi Trigger 632819449 / GRB 210120299)
  45. GRB 210120A: Fermi GBM Final Real-time Localization
  46. GRB 210112A: 3.6m DOT optical detection
  47. GRB 210119A (Swift J1851.2-6148): Swift-BAT refined analysis
  48. GECAM detection of a short GRB 210119A or a new SGR candidate Swift J1851.2-6148
  49. ZTF21aaeyldq: GROND observations
  50. GRB 210119A: Insight-HXMT/HE detection
  51. GRB 210119A: Fermi GBM observation
  52. ZTF21aaeyldq: LBT near-infrared observations
  53. GRB 210112A: Insight-HXMT/HE detection
  54. Short Fermi GRB 210119A or new SGR Swift J1851.2-6148: Possible MASTER Short OT detection
  55. Fermi GRB 210119A: Global MASTER-Net observations report
  56. Swift detection of a new SGR Swift J1851.2-6148 or a short GRB 210119A
  57. GRB 210119A: Fermi GBM Final Real-time Localization
  58. ZTF21aaeyldq CAHA 2.2m detection and power-law decay
  59. GRB 200613A: Host galaxy redshift from OSIRIS/GTC
  60. GRB 210112A: Deep CAHA 2.2m detection
  61. GRB 210104A: Late-time CAHA 2.2m detection
  62. Fermi trigger No 632573937: Global MASTER-Net observations report
  63. ZTF21aaeyldq: KPED observations
  64. Konus-Wind detection of GRB 210112A
  65. Correction to GCN 29288: NuEm-210111A: No counterpart candidates in INTEGRAL SPI-ACS observation
  66. ZTF21aaeyldq (AT2021any): Detection of X-ray Emission with Swift/XRT
  67. ZTF21aaeyldq: 2.2m CAHA BVRI optical observations
  68. GRB 201221D: near-infrared observation with LBT
  69. ZTF21aaeyldq: NOT optical observations
  70. ZTF21aaeyldq: Lowell Discovery Telescope observations
  71. ZTF21aaeyldq: observations with the 3.6m Devasthal Optical Telescope
  72. ZTF21aaeyldq: GTC Redshift and GRB afterglow nature confirmation
  73. GRB 201015A: evidence of supernova in LBT spectra
  74. ZTF Discovery of ZTF21aaeyldq (AT2021any): a Hostless, Young, and Rapidly Fading Transient
  75. GRB 210104A: JCMT SCUBA-2 sub-mm observations
  76. GRB 210112A: Swift/UVOT Detection
  77. GRB 210112A: Mondy optical observations
  78. GRB 210112A: 1.3m DFOT Optical upper limit
  79. GRB 210112A: OSN second epoch, decay
  80. GRB 210104A: AstroSat CZTI detection
  81. NuEm-210111A: MAXI/GSC upper limit
  82. GRB 210112A: Swift-BAT refined analysis
  83. GRB 210112A: OSN Reddened Afterglow Detection
  84. GRB 210112A: Swift-XRT refined Analysis
  85. NuEm-210111A : No neutrino counterpart in ANTARES
  86. GRB 210112A: AGILE detection
  87. GRB 210112A: Kitab a optical upper limit
  88. GRB 210104A: AROMA-N Optical Afterglow Detection
  89. GRB 210112A: Enhanced Swift-XRT position
  90. GRB 210112A: Swift detection of a burst with an optical counterpart
  91. NuEm-210111A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  92. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-210111A
  93. GRB 210104A: Mondy optical observations, light curve
  94. MAXI GRB210110.64: Global MASTER-Net observations report
  95. GRB 210110A: MAXI/GSC detection
  96. GRB 210104A: Assy continued optical observations, correction to GCN circ. 29265
  97. GRB 210109A: MAXI/GSC detection
  98. GRB 201227A: continued Chilescope confirmation of variability of possible optical counterpart, redshift estimating
  99. Correction to GCN 29278: GRB 201216C XRT refined analysis
  100. GRB 210108A: BALROG localization (Fermi Trigger 631793415 / GRB 210108424)

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