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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"

20967 results found.

  1. GRB 241127A: Swift/UVOT Detection
  2. GRB 241127A: LCOGT (40-cm) optical counterpart detection
  3. EP241126a: WFST Observations
  4. IceCube Alert 241127.59: Global MASTER-Net observations report
  5. Swift GRB241127.91: Global MASTER-Net observations report
  6. LIGO/Virgo/KAGRA S241125n: Swift-UVOT Upper Limits
  7. LIGO/Virgo/KAGRA S241127aj: NED Galaxies in the Localization Volume
  8. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations (duplicate submission of 38345)
  9. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations (duplicate submission of 38345).
  10. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations
  11. EP241126a: Optical Upper limits with Kinder observations
  12. EP trigger ID 01709122294: 1.6m Mephisto multi-band optical observations
  13. EP241126a: GSP detects optical counterpart
  14. EP241126a: TRT optical counterpart detection
  15. EP241126a: EP detection of a fast X-ray transient
  16. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on Optical Counterparts to Two of the Swift/XRT Sources
  17. LIGO/Virgo/KAGRA S241125n: SAGUARO follow-up observations with the MMT
  18. Trigger_18947: Swift ToO observations (retracted)
  19. LIGO/Virgo/KAGRA S241125n: DDOTI Optical Upper Limits
  20. LIGO/Virgo/KAGRA S241125n: Gaoyazi/GOT optical observations
  21. LIGO/VIRGO/KAGRA S241125n: GROWTH-India telescope optical observations
  22. LIGO/Virgo S241125n: Swift XRT observations, 5 X-ray sources
  23. LIGO/Virgo/KAGRA S241125n: HCT upper limit
  24. LIGO/Virgo/KAGRA S241125n: Upper limits from Konus-Wind observations
  25. GRB 241026A: radio detection with the VLA
  26. EP241125a: Optical upper limit with Kinder observations
  27. EP241125a: EP detection of an X-ray transient
  28. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on a Optical Counterpart at the BAT Position
  29. LIGO/Virgo/KAGRA S241125n: Upper limits from Fermi-GBM Observations
  30. LIGO/Virgo/KAGRA S241125n: Kinder optical upper limit in the BAT error region
  31. GRB 241113B: SVOM/VT optical afterglow observations
  32. GRB 241105A: ATCA radio detection
  33. GRB241120A: OHP/T193 optical observations
  34. EP241021a and EP241026b: Keck/LRIS spectroscopic observations
  35. EP trigger ID 01709065118: Keck/LRIS spectroscopic observations
  36. EP-WXT trigger 01709018832: Lick/Kast spectroscopy with the 3 m Shane telescope
  37. GRB 241120A: Mondy and AbAO optical observations
  38. EP241119a: Optical upper limits with Kinder observations
  39. EP241119a: GIT optical upper limits
  40. GRB 241113A: Possible ATCA Radio detection
  41. EP241119a : J-band observations with WINTER
  42. Integral GRB241120.25: Global MASTER-Net observations report
  43. EP241119a: Global MASTER-Net observations report
  44. EP241119a: EP detection of a fast X-ray transient
  45. GRB 241112B: Mephisto further optical observations
  46. GRB 241030A: J-band observations
  47. GRB 241115a: PRIME near-infrared upper limits
  48. Fermi GRB 241118A: Global MASTER-Net observations report
  49. Fermi GRB 241117B: Global MASTER-Net observations report
  50. Fermi GRB 241117A: Global MASTER-Net observations report
  51. GRB 241115A: Swift-XRT afterglow detection
  52. EP241115a/GRB 241115D: Optical upper limits with Kinder observations
  53. Fermi GRB 241115B: Global MASTER-Net observations report
  54. EP241115a: Global MASTER-Net observations report
  55. EP241115a: EP detection of a fast X-ray transient
  56. EP241113a: No Detection in Fermi-GBM Observations
  57. Swift GRB 241115A: Global MASTER-Net observations report
  58. Fermi GRB 241115A: Global MASTER-Net observations report
  59. EP 241113a: LBT possible optical counterpart
  60. GRB 241113B: KAIT Optical Afterglow Candidate
  61. LIGO/Virgo/KAGRA S241114bi: Upper limits from Fermi-GBM Observations
  62. LIGO/Virgo/KAGRA S241114bi: Coverage and upper limits from MAXI/GSC observations
  63. GRB 241113A: PRIME near-infrared upper limits
  64. Fermi GRB 241114A: Global MASTER-Net observations report
  65. EP241113a: Global MASTER-Net observations report
  66. GRB 241113B: J-band upper limit from WINTER
  67. GRB 241113A: J-band observations with WINTER
  68. EP241113a : J-band observations with WINTER
  69. GRB 241030A: LCO optical observation
  70. GRB 241113B: Swift-XRT observations
  71. GRB 241113A: 1.6m Mephisto and 50cm array optical upper limits
  72. GRB 241113A: KAIT optical observations
  73. EP241113b: Global MASTER-Net observations report
  74. Fermi-LAT gamma-ray observations of IceCube-241113A
  75. EP241113a: EP on-board trigger and autonomous follow-up observation
  76. EP241107a: SOAR upper limits
  77. GRB 241113A: Swift/UVOT Detection
  78. GRB 241113A: REM detection of the optical/NIR afterglow
  79. GRB 241113B: Swift ToO observations
  80. GRB 241113A: LCO optical observations
  81. GRB241113A: LCOGT (40-cm) optical counterpart detection
  82. GRB 241113A: MASTER010615.66-224018.2 optical counterpart detection
  83. Swift GRB241113.33: Global MASTER-Net observations report
  84. Fermi trigger No 753166198: Global MASTER-Net observations report
  85. GRB 241105A: ATCA Radio Upper Limits
  86. GRB 241112B: AbAO optical upper limit
  87. GRB 241107A: GROWTH-India telescope optical upper limit
  88. IceCube Alert 241113.02: Global MASTER-Net observations report
  89. Fermi GRB 241112A: Global MASTER-Net observations report
  90. GRB 241112B: Optical afterglow detection confirmation in revisiting the Mephisto data
  91. GRB 241112B: Swift-XRT afterglow detection
  92. GRB 241112B: SVOM/VT afterglow detection
  93. GRB 241112B: Mephisto optical upper limits
  94. GRB 241112B: GOTO optical upper limits
  95. GRB 241112B: Swift ToO observations
  96. EP241107a: EP-FXT follow-up observations
  97. LIGO/Virgo/KAGRA S241110br: NED Galaxies in the Localization Volume
  98. LIGO/Virgo/KAGRA S241109bn: ATLAS observations and discovery of the potential counterpart AT2024aawt
  99. Fermi trigger No 752990530: Global MASTER-Net observations report
  100. LIGO/Virgo/KAGRA S241109bn: Upper limits from EP-WXT observations

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