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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

19598 results found.

  1. EP241021a: SMA radio observation
  2. GRB 250113A: SVOM/GRM observation of a long burst
  3. EP250109b: optical upper limits with the Liverpool Telescope
  4. GRB 250106A: Swift-XRT afterglow detection
  5. EP250111a: KAIT optical observations
  6. GRB 250109A / EP250109a: Mephisto optical upper limits
  7. EP250108a: Mephisto detection
  8. EP250111a: Mondy optical observation
  9. EP250108a / AT 2025kg: LCO optical observations
  10. EP250111a: NOT likely optical counterpart
  11. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  12. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  13. EP-WXT trigger EP250108a：Xinglong optical follow-up observations
  14. GRB 250101A: CMO RC-500 optical observations
  15. EP250108a: NOT optical observations
  16. EP-WXT trigger EP250109a：Xinglong optical follow-up observations
  17. GRB 250109a: GMG Optical Upper Limit
  18. EP250109a: Swift/UVOT non-detection
  19. IPN triangulation of GRB 250107D (short/hard)
  20. EP250108a: Liverpool Telescope likely optical counterpart
  21. GRB 250108B: Gemini-North likely redshift z = 2.197
  22. GRB 250108B: 1.3m DFOT upper limit
  23. GRB 250108B: REM optical/NIR upper limits
  24. EP250109a: Global MASTER-Net observations report
  25. GRB 250101A: Terskol K-800 optical observations
  26. EP250109a: Swift/XRT non-detection
  27. GRB 250108A: Swift/UVOT Upper Limits
  28. GRB 250108A: NOT optical upper limit
  29. EP250108a: EP-WXT detection of an X-ray transient
  30. LIGO/Virgo/KAGRA S250109f: Identification of a GW compact binary merger candidate
  31. GRB 250103A: 1.6m Mephisto optical observations
  32. GRB 250108A: Swift-XRT afterglow detection
  33. GRB 250108A:SVOM/VT optical candidate
  34. LIGO/Virgo/KAGRA S250108eo: Identification of a GW compact binary merger candidate
  35. GRB 250108B: Swift/UVOT Upper Limits
  36. GRB 250103A: Swift-XRT afterglow detection
  37. GRB 250108B: Enhanced Swift-XRT position
  38. GRB 250108B: Swift detection of a burst
  39. GRB 250108A: Swift ToO observations
  40. GRB 250108A: SVOM detection of a soft long burst
  41. GRB 250107A: Swift ToO observations
  42. GRB 250101A: J band upper limit by SYSU 80cm telescope
  43. EPWXT01709129925: Xinglong optical observations
  44. GRB 250106A: NOT optical observations
  45. GRB 250103B: REM optical/NIR upper limits
  46. GRB 250101A: REM optical/NIR counterpart detection
  47. GRB 250106A: Swift ToO observations
  48. GRB 250106A: SVOM detection of a long burst
  49. GRB 250103B: Swift-XRT refined Analysis
  50. GRB 250103B: LCO/1m optical afterglow candidate detection
  51. GRB 250103A: Bassano Bresciano Observatory upper limit
  52. GRB 250101A: 1.3m DFOT optical afterglow detection
  53. GRB 241229A: 1.3m DFOT upper limit
  54. GRB 241228B: 1.3m DFOT Optical observations
  55. GRB 241228A: 1.3m DFOT upper limit
  56. LIGO/Virgo/KAGRA S250104v: Identification of a GW compact binary merger candidate
  57. GRB 250103A: Montarrenti Observatory optical detection
  58. GRB 250101A: further LCOGT optical afterglow observations
  59. GRB 250103A: TSHAO optical upper limit
  60. GRB 250103B: LCOGT Optical Upper Limit
  61. EP250101a: Liverpool Telescope optical upper limit
  62. GRB 250103A: Swift ToO observations
  63. GRB 250101a: Liverpool Telescope optical follow-up
  64. GRB 250103B: SVOM detection of a long burst
  65. GRB 250103B: Swift detection of a burst
  66. GRB 250103A: Xinglong 2.16m Optical Candidate
  67. GRB 250101B: SVOM/GRM observation
  68. GRB 250103A: GOTO optical upper limit
  69. GRB 250103A: SVOM/C-GFT optical upper limit
  70. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  71. EP241231b: optical upper limit with the Liverpool Telescope
  72. GRB 250103A: SVOM detection of a long burst (duplicate submission)
  73. GRB 250103A: SVOM detection of a long burst
  74. EP250101a: Xinglong optical upper limit
  75. LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
  76. GRB 250101A: further SAO RAS optical observations
  77. GRB 250101A: LCO optical counterpart detection
  78. GRB 250101A: Swift/UVOT Detection
  79. GRB 250101A: 1.6m Mephisto multi-band optical followup
  80. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  81. GRB 250101A: LCOGT optical afterglow detection
  82. GRB 250101A: OASDG optical observations
  83. GRB 250101A: AKO Optical Afterglow Detection
  84. GRB 250101A: SAO RAS optical observations
  85. GRB 250101A: Enhanced Swift-XRT position
  86. GRB 250101A: SVOM/C-GFT early optical observations
  87. GRB 250101A : GIT optical detection
  88. GRB 250101A: GMG Optical Observation
  89. GRB 250101A: Swift detection of a burst with an optical counterpart
  90. LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
  91. LIGO/Virgo/KAGRA S250101k: Identification of a GW compact binary merger candidate
  92. GRB 241229B: Continued CrAO ZTSh observations
  93. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  94. GRB 241229B: SVOM/GRM observation
  95. LIGO/Virgo/KAGRA S241231bg: Identification of a GW compact binary merger candidate
  96. EP241217A: J band upper limit by SYSU 80cm telescope
  97. GRB 241229B: SAO RAS optical upper limit
  98. GRB 241228B: SAO RAS optical observations
  99. EP240702a: 7DT Optical upper limits
  100. GRB 240606B: 7DT Optical upper limits

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